Why Galaxies care about AGB Stars III A Closer Look in Space and Time

Conference Programme and Abstracts SCIENTIFIC ORGANIZING COMMITTEE: Hans Olofsson (chair) I. Cherchneff M. Groenewegen S. Höfner R.M. Humphreys A. Jorissen A. Karakas F. Kerschbaum (co-chair) T. Lebzelter C. Maraston M. Meixner B. Plez P. Whitelock H. van Winckel R. Wing M. Wittkowski

LOCAL ORGANIZING COMMITTEE: F. Kerschbaum (chair) J. Hron (co-chair) T. Lebzelter W. Nowotny R. Ottensamer Th. Posch and numerous helping hands!

CONFERENCE LOCATION: University Campus Vienna Hörsaalzentrum Hof 2 Spitalgasse 2 1090 Wien

EDITORS: V. Baumgartner R. Ottensamer

Vienna, July 2014

2 WELCOME TO VIENNA!

Dear participants,

We would like to welcome all of you to the conference “Why Galaxies Care About AGB Stars III. A Closer Look in Space and Time.” We are very glad to see that so many sci- entists decided to join us for a week of intensive discussion on the current developments in the field of AGB stars and their impact on galactic and extragalactic research.

In 2006, the subtitle of our conference series was “Their importance as actors and probes,” in 2010 we focused on “Shining Examples and Common Inhabitants.” This time, we want to zoom in and take “A Closer Look in Space and Time.”

The detailed and complex physics of the atmospheres of AGB stars are one focus. Their close environment – being part of a binary system or the interaction with the ISM is an- other. The mass loss process and its effect on the host systems forms the bridge from stellar to galactic and extragalactic astronomy. Finally, recently developed and future ob- serving tools and capabilities opening up new windows for us get special attention.

This conference is hosted by the Austrian Society for Astronomy and Astrophysics and the Department of Astrophysics at the University of Vienna. The meeting is co-sponsored by the Vienna Conference Bureau. We thank the Robert F.Wing Support Fund, the Faculty of Earth Sciences, Geography and Astronomy of the University of Vienna, the Austrian Science Fund and several other sponsors for generous support.

We hope you all have an excellent and stimulating conference and that you enjoy Austria and Vienna.

The LOC

3 CONTENTS and SCIENTIFIC PROGRAMME

TABLE OF CONTENTS Welcome...... 3 Scientific Programme ...... 4 Oral Presentations ...... 11 Poster Presentations ...... 81 Conference Information ...... 124 Social Programme ...... 125 Local Information, Maps ...... 126 List of Participants ...... 131 Sponsors ...... 137

4 Scientific Programme

SUNDAY, July 27, 2014

18:00 – 20:00 Registration and Welcome

5 SCIENTIFIC PROGRAMME

MONDAY, July 28, 2014

08:00 Registration 08:45 Welcome – Pascale Ehrenfreund, Thilo Hofmann, SOC, LOC 09:15 Remembering Oliver Chesneau – Eric Lagadec 09:22 Remembering Tom Lloyd Evans – Hans Van Winckel Introductory Talk 09:30 AGB Evolution: Complexities and Opportunities – A. Renzini 11 Complex Atmospheres 10:00 3D hydrodynamical simulations of evolved stars and observations of stellar surfaces – A. Chiavassa 12 10:30 Studying the generation of shock waves in AGB stars with 3D radiation-hydrodynamics simulations – B. Freytag 13 10:45 Coffee break and poster viewing 11:15 Mass loss and variability in evolved stars – M. Marengo 14 11:45 Time Variability of Molecular Line Emission in IRC+10216 – D. Teyssier 15 12:00 Period – mass-loss rate relation of Miras with and without technetium – S. Uttenthaler 16 12:15 Lunch break 14:00 Spatially resolving the complex atmosphere of cool evolved stars – K. Ohnaka 17 14:30 Evolved stars with complex atmospheres observed with SOFIA from the Stratosphere – N. Ryde 18 14:45 An Imaging Line Survey of the Oxygen-rich AGB star IK Tau with the Submillimeter Array – E. De Beck 19 15:00 Making water in carbon-rich AGB winds – R. Lombaert 20 15:15 Herschel Observations of extreme OH/IR stars: using H2O to probe the initial masses – K. Justtanont 21 15:30 Coffee break and poster viewing 16:00 Role of magnetic fields in the mass loss of evolved stars – W. Vlemmings 22 16:30 VLTI/AMBER studies of the atmospheric structure and fundamental parameters of red giant and supergiant stars – B. Arroyo-Torres 23 16:45 Results from the VLTI/MIDI AGB Large Program – C. Paladini 24 17:00 Interferometric imaging diagnostics of circumstellar environments – X. Haubois 25 Living together 17:15 Observations of binaries (with focus on PPN and PN) – Olivier Chesneau/Eric Lagadec 26 17:45 End of the first day 18:30 Vienna city walking tour

6 SCIENTIFIC PROGRAMME

TUESDAY, July 29, 2014

09:00 Announcements 09:05 PAH formation in O-rich evolved stars – L. Guzman-Ramirez 27 09:20 Duplicity and its part in AGB evolution and nucleosynthesis – R. Izzard 28 09:50 Chemical abundance analysis of the symbiotic red giants – C. Galan 29 10:05 Binarity among carbon-enriched stars – S. Van Eck 30 10:20 The Circumstellar Environment of R Coronae Borealis: White Dwarf Merger or Final Helium Shell Flash? – G.C. Clayton 31 10:35 Interferometrically resolving post-AGB disks – M. Hillen 32 10:50 Coffee break and poster viewing 11:20 Smoothed Particle Hydrodynamics (SPH) models of AGB stars in binaries – S. Mohamed 33 11:50 Winds of binary AGB stars as observed by Herschel – A. Mayer 34 12:05 Shaping the outflows of binary AGB stars – S. Ramstedt 35 12:20 Lunch break 14:00 Shaping circumstellar environments of evolved stars: CSM-ISM interaction – N. Cox 36 14:30 Asymmetries in AGB stars: new results from aperture masking techniques – C. Lykou 37 14:45 VLT/NACO imaging of the nearest AGB star L2 Puppis – M. Montarges 38 What is left 15:00 Calibrating the role of TP-AGB stars in the cosmic matter cycle – P. Marigo 39 15:30 Coffee break and poster viewing 16:10 Post-AGB stars in the Magellanic Clouds as tracers of the s-process nucleosynthesis – K. De Smedt 40 16:25 Nucleosynthesis in Super-AGB stars – C. Doherty 41 16:40 Extra mixing and isotope ratios in AGB stars – R.J. Stancliffe 42 16:55 Modeling stellar interiors and nucleosynthesis of AGB stars – O. Straniero 43 17:25 The role of AGB stars in the cosmic fluorine production – H. Jönsson 44 17:40 End of the second day 19:00 Public talk: Rote Riesen, weiße Zähne und ALMA – M. Maercker

7 SCIENTIFIC PROGRAMME

WEDNESDAY, July 30, 2014

09:00 Announcements 09:10 Does the main component of the s-process in AGB stars constrain the neutron source in the 13C-pocket? – O. Trippella 45 09:25 The challenges of abundance analysis for long period variables – T. Lebzelter 46 09:40 Nucleosynthesis in AGB stars traced by isotopic ratios – R. De Nutte 47 09:55 The 12CO/13CO-ratio in AGB stars of different chemical type – H. Olofsson 48 10:10 The dust return from AGB stars in nearby galaxies – S. Srinivasan 49 10:40 Coffee break and poster viewing Old & new dust 11:10 Dust formation in AGB stars – I. Cherchneff 50 11:40 End of the third day 12:30 Leaving for Wachau trip

8 SCIENTIFIC PROGRAMME

THURSDAY, July 31, 2014

09:00 Announcements 09:05 Dust formation in the inner wind of the oxygen-rich AGB star IK Tau – D. Gobrecht 51 09:20 Interferometric constraints on molecule and dust formation in oxygen-rich Mira stars – M. Wittkowski 52 09:35 Wind acceleration in AGB stars: Solid ground and loose ends – S. Höfner 53 10:05 Exploring mass-loss in M-type AGB stars – S. Bladh 54 10:20 Amorphous aluminum oxide grains as the wind drivers in WHya – T. Khouri 55 10:35 The problematically short superwind of OH/IR stars - Probing the outflow with the 69 micrometer spectral band of forsterite – B. De Vries 56 10:50 Coffee break and poster viewing 11:20 Dust production from sub-solar to super-solar metallicity in Thermally Pulsing AGB Stars – A. Nanni 57 11:35 EvolutioN of Grains in the MAgellanic clouds (ENiGMA) – M. Meixner 58 11:50 Dust in the early universe and the contribution of AGB stars – R. Schneider 59 12:20 Lunch break 14:00 Metallicity dependence of oxygen-rich dust around evolved stars – O. Jones 60 14:15 How important are metal-poor AGB stars as cosmic dust producers? – L. Mattsson 61 Resolved and unresolved Populations 14:30 Nucleosynthesis in Helium-enriched AGB models: Implications for Globular Clusters – A. Karakas 62 14:45 Results from the PHAT project – L. Girardi 63 15:15 Constraining Mass Loss & Lifetimes of Low Mass, Low Metallicity AGB Stars – P. Rosenfield 64 15:30 Coffee break and poster viewing 16:10 The photometric and stellar properties of carbon stars in the Small Magellanic Cloud – G.C. Sloan 65 16:25 Post-AGB stars in the Magellanic Clouds – D. Kamath 66 16:40 Presenting Optical Spectra of AGB Stars in M31 – K. Hamren 67 16:55 AGB populations of LG dwarf spheroidals – J. Menzies 68 17:25 An Infrared Census of Extreme AGB Stars in Nearby Dwarf Galaxies – M. Boyer 69 17:40 End of the fourth day 19:30 Conference dinner at the University Observatory

9 SCIENTIFIC PROGRAMME

FRIDAY, August 01, 2014

09:00 Announcements 09:05 Model constraints from observations of active galaxies – R. Riffel 70 09:35 Probing the Sagittarius Tidal Streams with LPV Carbon Stars – A. Huxor 71 09:50 Phase-lag distances of OH masing AGB stars – D. Engels 72 Perspectives 10:05 Stellar astrophysics with the ELT – G. Bono 73 10:35 Coffee break and poster viewing 11:05 MIR/FIR space prospects for research on AGB stars – J. Blommaert 74 11:35 E-ELT MIR and MATISSE prospects for AGB-stars – J. Hron 75 11:50 Exploring the contribution of AGB stars to the Galactic chemical inventory using isotopic ratios – A. Goswami 76 12:05 Lunch break 13:45 Prospects for research on AGB stars and RSGs with long baseline interferometers and adaptive optics – G. Perrin 77 14:15 The ALMA view of evolved stars – M. Maercker 78 14:45 Analytical models of stellar winds to interpret ALMA data – W. Homan 79 15:00 The Wind Acceleration Region of Betelgeuse: Resolved at Centimeter Wavelengths – E. O’Gorman 80 15:15 Summary panel – B. Aringer, H. Van Winckel, M. Groenewegen, S. Höfner, M. Meixner 15:45 End of the conference

10 Oral Presentations

The talks appear in this booklet in the same order as in the programme.

Introductory Talk

AGB Evolution: Complexities and Opportunities

A. Renzini Invited

In this introductory talk, it will be attempted to illustrate why the AGB phase of stellar evo- lution is an especially difficult one to model or even to reconstruct in a phenomenological way. Macroscopic mass motions in stars are always the physical processes where our modelling is weakest and we are forced to parametrize them. But in AGB stars convec- tion, mixing, mass loss, pulsation (and perhaps even rotation) are very strongly coupled to each other in an apparently inextricable fashion. Even if our parametrizations were an adequate representation of these processes, so far only a minimal fraction of the parameter space has been explored. Yet, in spite of these enduring difficulties, recent observational developments have opened new opportunities for a better understanding of the main outcomes of AGB evolution.

11 Session 1: Complex Atmospheres

3D hydrodynamical simulations of evolved stars and observations of stellar sur- faces

A. Chiavassa Invited

Nowadays, the development of the observational instruments is so high that they became very sensitive to the details of stellar surfaces. The interpretation of the images of stellar surfaces, the fundamental parameters, the stellar variability need realistic simulations of stellar convection. Three-dimensional radiative hydrodynamics simulations of evolved stars are essential to a proper and quantitative analysis of these observations. I will present how these simulations have been (and will be) crucial to prepare and interpret the spectrophotometric, interferometric, astrometric, and imaging observations of these stars that strongly enrich the chemical evolution of our Galaxy.

12 Studying the generation of shock waves in AGB stars with 3D radiation- hydrodynamics simulations

B. Freytag

In the sun, small-amplitude, small-scale acoustic waves are just detectable in the photo- sphere and start to become dynamically relevant only in the lower chromosphere. The generation of these waves by non-stationary convective flows can be studied by local 3D radiation-hydrodynamics models. Using this technique for global models of AGB stars reveals roughly similar phenomena but on a larger scale and with much larger ampli- tude. Convection cells spanning a significant fraction of the entire surface produce strong waves that cause a network of smaller shocks in the inner photosphere and occasional global shocks, travelling outward almost radially symmetric. Material falling back inter- acts with the surface convection cells. Recent numerical simulations of these layers with CO5BOLD will be presented together with a discussion of their expected impact on the dust and wind formation processes further out.

13 Mass Loss and Variability in Evolved Stars

M. Marengo Invited

Mass loss is a fact of life for evolved stars. At the same time, however, it is their lead- ing cause of death: stellar winds deplete the convective envelope of low and intermediate mass stars, stunting their nuclear burning, and sending them to the white dwarf graveyard. But mass loss is also an agent of rebirth, as it plays a crucial role in releasing recently synthesized elements from the grip of stars’ gravity well, driving the chemical evolution of galaxies. Our understanding of stellar mass loss has progressed enormously in the last decade, thanks to the availability of infrared telescopes from space and new millimeter and radio interferometers from the ground. These new facilities have extended our obser- vational reach from the Milky Way to nearby galaxies, allowing us to quantify mass loss processes for almost complete stellar samples in a variety of environments. At the same time, sophisticated stellar models are used to simulate the processes driving outflows in evolved stars’ atmospheres. In this talk I will review our current understanding of mass loss in evolved stars, with a particular focus on AGB stars and the links with the stellar pulsation processes powering their outflows.

14 Time Variability of Molecular Line Emission in IRC+10216

D. Teyssier, J. Cernicharo, G. Quintana-Lacaci, J. Pearson, L. Decin, M. Agundez, E. de Beck, F. Daniel, M. Barlow, P. Garcia-Lario, M.A.T. Groenewegen, D. Neufeld

We present the result of a monitoring of the molecular emission in the C-rich AGB star IRC+10216 over 3 years with the Herschel Space Observatory. Rotational transitions of 13 various vibrational levels of CO, CO, CS, CCH, H2O, SiO, SiS, SiC2, HCN and HNC (among others) have been collected with the HIFI, PACS and SPIRE instruments over re- spectively 6 (or 7), 7 and 8 epochs. Together with those data, synchronized observations have also been obtained in low excitation transitions of the same species at the 30-m tele- scope. While IRC+10216, like all Mira-type stars, shows significant amplitude modulation in the visible and the IR (e.g. 2 mag in the I band over a period of 635 days, Alksnis et al. 1989), variation in the rotational levels of many of those molecular species (excited mainly through collision) was shown to be negligible, especially in the outer shell (Cernicharo et al. 2000). With Herschel probing more inner layers of the envelope, the intensity moni- toring shows strong and periodic variations of most of the observed molecules (in excess of 1000% in e.g. CCH), often with differential behaviour depending on the transition level (larger variation at higher J), and generally enhanced oscillation in the vibrational modes of some of these molecules (e.g. HCN). As expected, the intensity modulation exhibits a time lag compared to the IR light-curve, allowing to infer the typical distance to the star of the zone contributing the most to the considered line emission. These results show that the effect of IR pumping through the different vibrational levels on the emergent line profiles of a given transition can be really significant. This implies that the IR radiation field of circumstellar envelopes and its time variation has to be taken into account in any radiative transfer model in order to derive the accurate physico-chemical structure of the envelope. In this contribution we will give an overview of the variation profiles of over 80 molecular lines, and draw some early conclusions on how the excitation regime is discriminating the modulation of the probed emission.

15 Period – mass-loss rate relation of Miras with and without technetium

S. Uttenthaler

We present new results on the investigation of the location of Miras with and without technetium (Tc) in the (K-[22]) vs. pulsation period diagram (Uttenthaler 2013, A&A 556, A38). It was found that Miras occupy different regions in this diagram, dependent on the presence of the third dredge-up indicator Tc. If the Tc-distinction is made, a clear relation between dust mass-loss rate (K-[22]) and pulsation period is revealed. Surprisingly, at a given period, the Tc-poor Miras have a higher dust mass-loss rate than the Tc-rich Miras. We put forward possible explanations for this counter-intuitive behavior. It is possible that this finding could teach us an important lesson about connections between dredge-up, pulsation behavior and the mass-loss mechanism of evolved AGB stars, which we need to understand.

16 Spatially resolving the complex atmosphere of cool evolved stars

K. Ohnaka Invited

The mass loss from cool evolved stars (red giants, AGB stars, and red supergiants) is one of the long-standing problems in stellar astrophysics. For identifying the driving force of the mass loss, it is essential to understand the physical properties of the region from the outer atmosphere to the innermost circumstellar envelope. The recent progress in high spatial resolution observations has enabled us to spatially resolve this key region and reveal its complex nature. Now we can image inhomogeneous structures over the surface of stars and in the atmosphere. Combination of high spatial and high spectral resolution even allows us to spatially resolve the gas dynamics over the surface of stars – just as in Solar physics. In this talk, I will review recent results of high spatial resolution observations of cool evolved stars and discuss implications to the mass-loss mechanism.

17 Evolved stars with complex atmospheres observed with SOFIA from the Strato- sphere

N. Ryde, M. Richter, J. Lambert, E. Josselin, G. Harper; SOFIA/EXES science team

A wide range of evolved stars have shown to have complex outer atmospheres; from AGB stars to red giants in general. There are a number of, sometimes unexpected, observational indications that a majority of these stars, from K giants and cooler, have molecular layers around them (MOLspheres). These, often ignored, molecular layers affect the line formation in these stars and their observed spectra, and therefore our interpretation of them. Here, we present high-resolution spectra of water vapour of a range of K and M giants observed with EXES on board SOFIA. These spectra pose strong constraints on the modelling of the outer atmospheres of these stars, including the MOLsphere. In the modelling, we have developed a new method to treat large atoms and molecules, such as water, in non-LTE. Our modelling indicates that there will be a severe extra molecular cooling. It further shows that some lines are overpopulated whereas others are underpopulated, affecting directly the interpretation. We discuss how these findings affect the assumption of the existence of a MOLsphere surrounding the warmer of the stars.

18 An Imaging Line Survey of the Oxygen-rich AGB star IK Tau with the Submillime- ter Array

E. De Beck, K. M. Menten, T. Kaminski, N. Patel, K. Young

Dedicated, unbiased spectral scans of AGB stars have so far only been published for a few C-type stars, such as IRC+10216. I present results from a spectral survey of the circumstellar envelope of the high-mass-loss-rate M-type AGB star IK Tau obtained with the SMA at ∼ 0.7" spatial resolution in the frequency range 279-355 GHz, expanding the molecular inventory for M-type evolved stars and filling an observational gap. The survey shows more than 200 emission lines, belonging to ∼ 20 species. The vibrationally excited emission of e.g. H2O, SiO, SiS, and NaCl traces the acceleration of the wind in the inner 45 stellar radii, while the emission of isotopologues of CO, SiO, SiS, HCN, SO, and SO2 lets us constrain the AGB nucleosynthesis of IK Tau. I will highlight the first detection of PO and PN around an M-type AGB star, detected at unexpectedly high abundances, and emphasise the importance of unbiased spectral surveys of AGB stars and the need for updated chemical models.

19 Making water in carbon-rich AGB winds

R. Lombaert, L. Decin, P. Royer, A. de Koter, N.L.J. Cox, J. De Ridder, T. Khouri, M. Agúndez, J.A.D.L. Blommaert, J. Cernicharo, E. González-Alfonso, M.A.T. Groenewegen, F. Kerschbaum, D. Neufeld, B. Vandenbussche, C. Waelkens

The recent detection of warm water vapor emission from carbon-rich winds of asymptotic- giant-branch (AGB) stars challenged the current understanding of circumstellar chem- istry. Water emission detected with the PACS instrument onboard the Herschel Space Telescope allows us to constrain which water formation mechanism is responsible in these environments. We report the detection of warm water emission close to or inside the acceleration zone of ALL eighteen carbon-rich sample stars, irrespective of their stellar or circumstellar properties. We find an anticorrelation between the water/CO line-strength −7 ratios and the mass-loss rate for rates higher than M˙ g > 3 × 10 M /yr, regardless of the upper-level energy of the relevant transitions. This implies that the water formation mechanism becomes less efficient with increasing envelope column density. The anti- correlation breaks down for the lowest mass-loss-rate sources, the SRb objects, which clump together at an overall lower water abundance. Finally, the large sample of de- tected water lines provides meaningful constraints on the dust-to-gas ratio in carbon-rich environments, trending towards the lower values around 0.001. Based on these findings, we can suggest that a combination of pulsationally induced shocks and ultraviolet pho- todissociation could in principle explain the properties of water emission from carbon-rich circumstellar environments.

20 Herschel Observations of extreme OH/IR stars: using H2O to probe the initial masses

K. Justtanont, J. Blommaert, D. Teyssier, B. Swinyard, M. Barlow, J. Cami, L. Decin, F. Kerschbaum, M. Matsuura, H. Olofsson, P. Owen, R. Waters, J. Yates

Extreme OH/IR stars are classified by the presence of a very dusty circumstellar enve- lope, showing the silicate bands in absorption. Many exhibit the recent sudden increase in the mass loss rate, along with the presence of crystalline silicates. Recent observa- tions using the Herschel Space Observatory showed the lack of 18O compared to 16O and 17O which is in line with the stars undergoing hot-bottom-burning. Stellar evolution calculations put a lower limit of this process at 4-5 solar masses for solar abundances, indicating that these OH/IR stars evolve from intermediate-mass stars. We present new Herschel spectra of these extreme OH/IR stars using HIFI and SPIRE. From the observed H2O lines, we are able to detect two of the three isotopologues, expanding the sample of intermediate-mass AGB stars.

21 Magnetic fields and the mass loss of evolved stars

W. Vlemmings Invited

While significant progress has been made in the study of AGB mass-loss, the effect of magnetic fields is yet poorly studied. The mass lost in the last phases of stellar evolution will, for select sources, become visible as a spectacular planetary nebula (PN). These are however often not spherically symmetric, and the shaping process, linked with the mass loss in the late AGB, post-AGB and pre-PNe phases, remains elusive. Both bina- ries and magnetic fields have been suggested to be possible agents although a combi- nation of both might also be a natural explanation. In this talk I will review the current evidence for magnetic fields around AGB and post-AGB stars pre-Planetary Nebulae and PNe themselves. Magnetic fields appear to be ubiquitous in the envelopes of ap- parently single stars, challenging current ideas on its origin, although we have found that binary companions could easily be hidden from view. There are also strong indications of magnetically collimated outflows from post-AGB/pre-PNe objects supporting a significant role in shaping the circumstellar envelope. This talk will mainly focus on centimeter and (sub)millimeter wavelength observations and will also highlight how ALMA will provide a huge leap in our ability to study the magnetic fields around late-type stars.

22 VLTI/AMBER studies of the atmospheric structure and fundamental parameters of red giant and supergiant stars

B. Arroyo-Torres, M. Wittkowski, J. M. Marcaide, F. J. Abellan, A. Chiavassa, J. Fabregat, J. C. Guirado, P. H. Hauschildt, I. Marti-Vidal, A. Quirrenbach, M. Scholz, P. R. Wood

We present recent near-IR interferometric studies of red giant and supergiant stars, which are aimed at obtaining information on the structure of the atmospheric layers and at con- straining the fundamental parameters of these objects. The observed visibilities of the red supergiants (RSGs) and also of one of the red giants indicate large extensions of the molecular layers, as those previously observed for Mira stars. These extensions are not predicted by hydrostatic PHOENIX model atmospheres, hydrodynamical (RHD) sim- ulations of stellar convection, or self-excited pulsation models. All these models based on parameters of RSGs lead to atmospheric structures that are too compact compared to our observations. We will discuss how alternative processes might explain the atmo- spheric extensions for these objects. As the continuum appears to be largely free of contamination by molecular layers, we can estimate reliable angular Rosseland radii of our stars. Together with distances and bolometric fluxes, we estimate the effective tem- peratures and luminosities of our targets, locate them in the HR diagram, and compare their positions to recent evolutionary tracks.

23 Results from the VLTI/MIDI AGB Large Program

C. Paladini, D. Klotz, S. Sacuto, E. Lagadec, M. Wittkowski, A. Richichi, J. Hron, A. Jorissen, M. Groenewegen, F. Kerschbaum, G. Rau, T. Verhoelst, H. Olofsson

In August 2010, during the last AGB conference, we decided to write a Large Program to observe a subsample of AGB stars from the Herschel Mass-Loss of Evolved StarS (MESS) program with the VLTI MID-infrared Interferometric instrument (MIDI) and with the VLT Imager and Spectrometer for mid Infrared (VISIR). The idea was to provide an insight in the atmosphere of those stars, to be able to understand the role of the mass-loss process at different spatial scales. In this contribution I will present the results of the MIDI campaign. We obtained visibilities and spectra for fifteen objects with different chemistry and variability class. These observations, together with the data we retrieved from the archive, allowed us not only to characterise the geometry, but in some cases also the time variability in the N-band. As previously reported in literature, we confirm the detection of spectroscopic variability, but not interferometric. This result has implications on the size of the structures involved in the dust formation process. We also report two cases of asymmetric structures. While the nature of those structures will be clearly identified only with the second generation VLTI instrument MATISSE, the data indicate that overall in our sample, between 5 and 10 stellar radii, there are no pronounced aspherical structures, such as discs.

24 Interferometric imaging diagnostics of circumstellar environments

X. Haubois, M. Wittkowski, G. Perrin, P. Kervella, S. Ridgway

Optical interferometry is a powerful tool to investigate the close environment of AGB stars. With a spatial resolution of a few milli-arcseconds, it is even possible to image directly the surface of angularly large objects. This is of special interest for Mira stars and red supergiants for which the dust-wind is initiated from or very close to the photosphere by an interplay between pulsation and convection. Based on several-epoch interferometric observations of one Mira star, I will present how the variation of the angular size with wavelength challenge pulsation models and how reconstructed images can reveal the evolution of the object shape and of asymmetric structures. Moreover, I will also present some interfero-polarimetric observations of the red supergiant Betelgeuse that probe its inner dusty environment and that put constraints on the dust properties.

25 Session 2: Living Together

Observation on binaries (with focus on PPN and PN)

E. Lagadec, O. Chesneau Invited

During the last years, many observational studies have revealed that binaries were play- ing an active role in the shaping of a non spherical planetary nebula. I will review the different works that lead to the direct or indirect evidence for binary companions during the AGB, PPN and PN phase. I will also discuss how these binaries can influence the stellar evolution and possible future directions in the field.

26 PAH formation in O-rich evolved stars

L. Guzman-Ramirez, E. Lagadec, D. Jones, A. A. Zijlstra, K. Gesicki

Polycyclic aromatic hydrocarbons (PAHs) have been observed in O-rich planetary neb- ulae towards the Galactic Bulge. This combination of oxygen-rich and carbon-rich ma- terial, known as dual-dust or mixed chemistry, is not expected to be seen around such objects. We recently proposed that PAHs could be formed from the photodissociation of CO in dense tori. In this talk, using VISIR/VLT, we spatially resolved the emission of the PAH bands and ionised emission from the [SIV] line, confirming the presence of dense central tori in all the observed O-rich objects. Furthermore, we show that for most of the objects, PAHs are located at the outer edge of these dense/compact tori, while the ionised material is mostly present in the inner parts of these tori, consistent with our hypothesis for the formation of PAHs in these systems. The presence of a dense torus has been strongly associated with the action of a central binary star and, as such, the rich chemistry seen in these regions may also be related to the formation of exoplanets in post-common-envelope binary systems.

27 Duplicity and its part in AGB evolution and nucleosynthesis

R. Izzard Invited

Half or more of all stars more massive than our Sun are orbited by a companion star in a binary system. Many binaries have short enough orbits that the evolution of both stars is greatly altered by the transfer of mass and angular momentum. Such mass transfer is highly likely on the AGB because this is when a star is both very large and has strong wind mass loss. Direct mass transfer truncates the AGB, and its associated nucleosyn- thesis, prematurely compared to in a single star. In wide binaries where one star has captured material from a long-dead AGB companion, we can probe the nucleosynthesis in the AGB primary star as well as the fundamental astrophysics of wind accretion and circumbinary disc formation. I will highlight recent quantitative work on nucleosynthesis in (ex-)AGB mass-transfer systems, such as carbon-enhanced metal-poor and barium stars, and suggest AGB stars as a possible source of the despicable element lithium. I will also review the workshop "Nucleosynthesis in AGB Stars" (in Bonn, July 2014), with the aid of embarrassing photographs and videos for the benefit of those who missed out on the fun.

28 Chemical abundance analysis of the symbiotic red giants

C. Galan, J. Mikolajewska, K. H. Hinkle

The study of symbiotic stars - the long period, interacting binary systems - composed of red giant donor and a hot, compact companion (mainly white dwarf occasionally re- placed by a neutron star) is important for our understanding of binary stellar evolution in systems where mass loss or transfer take place involving RGB/AGB stars. Knowledge of the elemental abundances of symbiotic giants is of special significance since they can be used to track mass exchange history and can help to understand better the latest stages of the binary evolution, that have impact on chemical evolution of the Galaxy, and forma- tion of the stellar populations. However, the number of these objects with fairly well de- termined photospheric composition is insufficient for statistical considerations, and most are G or K-type giants whereas the vast majority of symbiotic stars contain M-type giants. Here we present the detailed chemical abundance analysis obtained for the first time for about a dozen of M-type symbiotic giants. The analysis is based on the high resolution (R ∼ 50000), high S/N ∼ 100, near-IR spectra (at H- and K-band regions) obtained with Phoenix/Gemini South spectrometer. Spectrum synthesis employing standard LTE anal- ysis and atmosphere models was used to obtain photospheric abundances of CNO and elements around the iron peak (Sc, Ti, Fe, and Ni). Our analysis reveals in most cases slightly sub-solar or solar metallicities with [Fe/H] being in the range from approximately −0.45 to +0.15. We obtained a significantly sub-solar metallicity, [Fe/H] ∼ −0.75, for the RW Hya giant confirming its membership of the Galactic halo population. The very low 12C/13C isotopic ratios, ∼ 6−11, and significant enrichment in nitrogen 14N isotope in almost all giants in our sample indicate that they have experienced the first dredge-up.

29 Binarity among carbon-enriched stars

S. Van Eck, A. Jorissen, H. Van Winckel, T. Merle

Binarity is known to be a fundamental ingredient for the evolutionary path followed by several classes of carbon-enriched stars. For example, Barium stars, extrinsic S stars and CEMP stars are known to bear the AGB nucleosynthesis imprint of their (now ex- tinct) binary companion. However, binarity is difficult to demonstrate in several classes of carbon-enriched stars, either because they are faint or highly variable. Results of a radial-velocity monitoring with the HERMES spectrograph, mounted on the MERCATOR telescope (La Palma, Spain) will be presented concerning R, N, CEMP and AGB stars, including new binary detections.

30 The Circumstellar Environment of R Coronae Borealis: White Dwarf Merger or Final Helium Shell Flash?

G.C. Clayton, E. Montiel, P. Tisserand, D. L. Welch

In 2007, R Coronae Borealis (R CrB) went into an historically deep and long decline. In this state, the dust acts like a natural coronograph at visible wavelengths, allowing faint nebulosity around the star to be seen. Several of the structures around R CrB are cometary globules caused by wind from the star streaming past dense blobs. The es- timated dust mass of the knots is consistent with their being responsible for the R CrB declines if they form along the line of sight to the star. In addition, there is a large diffuse shell extending up to 4 pc away from the star containing cool 25 K dust that is detected all the way out to 500 µm. The evidence pointing toward a white-dwarf merger or a final- helium-shell flash origin for R CrB is contradictory. The shell and the cometary knots are consistent with a fossil planetary nebula. Along with the fact that R CrB shows significant Lithium in its atmosphere, this supports the final-helium-shell flash. However, the rela- tively high inferred mass of R CrB and its high fluorine abundance support a white-dwarf merger.

31 Interferometrically resolving post-AGB disks

M. Hillen, H. Van Winckel, T. Verhoelst, J. Menu, C. Gielen, M. Min, B. de Vries, et al.

In this contribution I wish to present the exciting results obtained with our interferomet- ric experiments of post-AGB disks. Binaries with circumbinary disks are very commonly found among optically bright post-AGB stars (see the contribution of D. Kamath). Al- though clearly linked to binary interaction processes, the formation, evolution and fate of these disks are still badly understood. Due to their compactness, interferometric tech- niques are required to resolve them. Here, I will present our high-quality multiwavelength interferometric data of two prototypical yet very different post-AGB binaries, i.e. AC and 89 Herculis, as well as the modeling thereof with radiative transfer models. By compar- ing both objects I will show the successes and limitations of these models which were developed for protoplanetary disks around young stars. Multiwavelength high-angular- resolution observations are indispensable to understand these complex and interacting objects, and their place in the grand scheme of the (binary) evolution of low and interme- diate mass stars.

32 Smoothed Particle Hydrodynamics (SPH) models of AGB stars in binaries

S. Mohamed Invited

The interaction of an AGB star with a stellar companion can lead to a wide range of unusual and spectacular phenomena, from spiral-shaped circumstellar outflows to vio- lent thermonuclear explosions. In this review, I will describe the complex interplay of processes involved in these binary interactions, e.g., stellar winds, accretion and wind Roche-lobe overflow (WRLOF), and the multi-dimensional, SPH simulations which have been used to model them. I will also discuss what we learn from the models about the mass transfer rates and the morphology of the circumbinary outflows in these systems. I will conclude with a discussion of the far reaching implications of this work for related systems, e.g., Type Ia supernovae, planetary nebulae and barium stars.

33 Winds of binary AGB stars as observed by Herschel

A. Mayer, A. Jorissen, F. Kerschbaum, R. Ottensamer, C. Paladini, M. Mecina, S. Mohamed

We present Herschel/PACS observations of the large-scale environments of binary AGB stars as part of the Mass loss of Evolved StarS (MESS) sample. From literature we found 18 of these objects to be members of physically related multiple systems. Several of these objects show a large-scale far-IR emission that differs significantly from spherical symmetry and is caused by the gravitational force of the companion on the stellar AGB wind and the mass loosing star itself. A spiral pattern is thereby imprinted in the dusty stellar wind. The most remarkable structures are found around o Ceti, R Aquarii and π1 Gruis. The environment of o Cet shows a spiral embedded in a bow shock while the symbiotic nature of R Aqr is revealed as two opposing arms which reflect a nova outburst. The emission around π1 Gru is dominated by two structures, an oblate disk like emission and an arm, which are presumably not caused by the same companion. We rather think that π1 Gru is a hierarchical triple system in which the close companion attracts the AGB wind onto the orbital plane and the outer companion forms a spiral arm. These far-IR observations underline the role of a companion as a major external influence in creating asymmetric winds in the AGB phase, even before the star becomes a PN.

34 Shaping the outflows of binary AGB stars

S. Ramstedt, W. Vlemmings, S. Mohamed

The required conditions for stars to evolve into planetary nebulae (PNs) continue to puz- zle. Since PNs are found in a wide variety of shapes, processes that could sculpt cir- cumstellar envelopes (CSEs) are being investigated. A binary companion will have a strong gravitational effect, but known binary AGB stars are rare. We have observed the CO emission from a small sample of known binary AGB stars (R Aqr, Mira, W Aql, and π1 Gru) with ALMA. The stars cover a decisive range in binary separation, neces- sary to provide essential constraints for 3D models of the binary interaction. They have previously been observed with Herschel/PACS and VLTI/MIDI allowing the circumstellar morphology to be studied from the very inner CSE out to the very largest scales. The circumstellar gas distribution will strongly depend on how the mass is initially lost from the primary. These observations will therefore not only help us understand the important processes for the binary interaction, but will also provide crucial information needed to understand the mass-loss mechanisms of the primary. The first set of observations has been delivered and I will present preliminary results.

35 Shaping circumstellar environments of evolved stars: CSM-ISM interaction

N. Cox Invited

The circumstellar envelopes of AGB stars and Red Super Giants are complex chemical and physical environments. Understanding them is important for both stellar and galaxy evolution. One key aspect in this is to understand how the circumstellar medium of these stars is shaped and affected by ’internal’ and ’external’ mechanisms. This can alter our view on the (dust) chemistry and mass-loss history of these stars, and hence their role in chemical enrichment of galaxies. This presentation focuses on the ’external’ mechanism related to the interaction of the slow dusty stellar wind and the local ambient medium; I will discuss what recent infrared observations and hydrodynamical simulations have revealed and how these can help us learn more about AGBs and RSGs as well as the interstellar medium.

36 Asymmetries in AGB stars: new results from aperture masking techniques

F. Lykou, J. Hron, D. Klotz, C. Paladini, A. Zijlstra, P. Tuthill, B. Norris, J. Kluska, E. Lagadec, O. Chesneau, J. Monnier

It has been argued for many years now, that asymmetries found in the post-AGB stars and planetary nebulae should originate as early as during the AGB phase. I will present results of our high-angular resolution observing program on the VLT with the application of an aperture masking technique, which allowed us to detect asymmetries in the form of disk-like structures within only a few stellar radii around two AGB stars, one C-rich and one O-rich. Both stars exhibit also dimming events, when their visual and infrared magnitudes vary significantly and at periods much larger than the typical Mira values. I will argue on the importance of these characteristics as indicators of binarity and explain how studying such objects, which are probably in transition to the post-AGB phase, can shed more light in ejecta shaping agents.

37 VLT/NACO imaging of the nearest AGB star L2 Puppis

M. Montarges, P. Kervella, S. Ridgway, G. Perrin, O. Chesneau

AGB stars are the most important contributors to the chemical enrichment of the Galaxy. During their later evolutionary stages they experience intense pulsations and they eject most of their layers when becoming a planetary nebula (PN). The process leading to the formation of bipolar PN remains poorly understood. It is assumed that the circumstellar disk of an AGB star could collimate the stellar wind to form a bipolar PN, yet, very few of these disks were observed. Using the adaptive-optics system of the VLT/NACO instru- ment at the Paranal Observatory and a lucky imaging technique, our team obtained near infrared diffraction limited images of the nearest AGB star L2 Puppis. The deconvolved images reveal a dark structure in front of the star whose morphology and photometry are matching a dusty edge-on disk of olivine and pyroxene modeled with a Monte-Carlo radia- tive transfer code. The L band images also show a loop structure, possibly the signature of an interacting hidden companion.

38 Session 3: What is left

Calibrating the role of TP-AGB stars in the cosmic matter cycle

P. Marigo Invited

Despite TP-AGB stars play a critical role across astrophysics, the modelling of their evo- lution is still affected by large uncertainties that propagate into the field of extragalactic astronomy, impinging dramatically on the estimation of fundamental galaxy properties up to high redshift. In this context, I will review recent and ongoing efforts to calibrate the evolution of TP-AGB stars – specifically with respect to TP-AGB lifetimes, core mass growth, efficiencies of the third dredge-up and mass loss – using data from the Milky Way and nearby resolved galaxies.

39 Post-AGB stars in the Magellanic Clouds as tracers of the s-process nucleosyn- thesis

K. De Smedt, H. Van Winckel, D. Kamath, A.I. Karakas, L. Siess, S. Goriely

Post-AGB stars are ideal probes of the internal processes during the AGB phase. Their photospheres are dominated by atomic transitions allowing abundance determinations for a very wide range of elements, from CNO up to the most heavy s-process elements. The Galactic post-AGB star sample displays a strong chemical diversity, but the poorly known distances and hence luminosities and initial masses hamper the interpretation in the broader context of (chemical) stellar evolution. To overcome these limitations, we perform chemical studies of post-AGB stars in the Magellanic Clouds. We will review our results obtained so far and report on the most interesting discrepancies between observations and model predictions. We focus on the challenges regarding C, O and the s-process elements including lead (Pb). We will report on the implications of our findings on our understanding of the AGB nucleosynthesis and mixing processes.

40 Nucleosynthesis in Super-AGB stars

C. Doherty, P. Gil-Pons, M. Lugaro, H. Lau, J. Lattanzio, L. Siess, S. Campbell

Super-AGB stars reside in the mass range ∼ 6.5 − 10 M and are characterised by off- centre carbon ignition prior to a thermally pulsing AGB phase. These stars can undergo from many tens to even thousands of thermal pulses and experience extreme nucleosyn- thetic conditions, with temperatures at both the base of the convective envelope, and within the helium burning intershell regions far higher than in their lower mass counter- parts. This can result in interesting nuclesynthesis from extreme hot bottom burning and also different heavy element distributions caused by the high neutron density generated within the thermal pulse, with this material later mixed to the surface during third-dredge up events. The most massive super-AGB stars can also undergo a dredge-out event, where, near the end of the carbon burning a convective helium burning region forms which merges with the inward moving convective envelope. When these zones meet, hy- drogen is mixed down to very high temperature regions with this proton ingestion episode leading to the formation of a 13C pocket, subsequent neutron release and heavy element production. We present heavy element nucleosynthetic yield predictions for super-AGB stars for a wide range of metallicities from Z = 0.02−0.0001 ([Fe/H] ∼ 0 to −2.3) with par- ticular focus on the dredge-out nucleosynthesis results. We investigate the impact that uncertainties such as the mass-loss rate, nuclear reaction rates or efficiency of convec- tive mixing have on heavy element production. We then apply our nucleosynthetic yield predictions to examine the possible role of super-AGB stars as polluters of the anomalous stars within globular clusters or as a source of light s-process elements such as Sr in the early Galaxy.

41 Extra mixing and isotope ratios in AGB stars

R. J. Stancliffe

In nearly all computations of the evolution of AGB stars, convection is the sole means by which material can be transported within the stellar interior. However, these models fail to account for some of the observed properties of AGB stars and the measurements of pre-solar grains. It has long been postulated that some circulation of material below the convective envelope may take place and hence influence the nucleosynthesis of the light elements. I will discuss how two processes, namely thermohaline mixing and dif- fusive overshooting, affect the nucleosynthesis in low mass AGB stars across a range of metallicities, with a particular focus on how the isotopic ratios of various elements are modified.

42 Modeling stellar interiors and nucleosynthesis of AGB stars

O. Straniero Invited

More than 40 years have passed since Weigert (1966) and Schwarzschild & Harm (1967) discovered the occurrence of thermal pulses during the AGB, but these stars are still a major challenge for stellar modelers, for several reasons. Numerical algorithms and input physics should be particularly accurate to properly follow significant variations of the physical and chemical structure on relatively small temporal and spatial steps. Many efforts have been made to improve the physical description of these stars and a qualitative agreement is generally found between models produced by different groups, although quantitative results may be rather different. We review the state of the art, discussing, in particular the physical processes expected to produce major uncertainties on AGB calculations.

43 The role of AGB stars in the cosmic fluorine production

H. Jönsson, N. Ryde, et al.

The cosmic origin of fluorine has not been established. Production of fluorine has been observationally proven in AGB-stars, but it is uncertain if the amount of fluorine produced can explain the cosmic abundance. Over the years there have been claims both for and against AGB-stars being the most dominant fluorine producer in the Galaxy. Other pro- posed production sites are Wolf-Rayet stars and supernovae Type II via the ν-process. The molecular data of the HF molecule, that is used for fluorine abundance determina- tion, has never been properly published and is most likely incorrectly used in several earlier works leading to ∼ 0.3 dex too high fluorine abundance. Here, I will present an ongoing project with the goal of constraining the possible production sites of fluorine and in particular the role of the AGB stars. The project includes several observational data sets of different stellar populations, calculations of molecular data, and galactic chemical evolution modelling.

44 Does the main component of the s-process in AGB stars constrain the neutron source in the 13C-pocket?

O. Trippella, M. Busso, E. Maiorca, F. Käppeler, S. Palmerini

The main component of the s-process is mainly produced in low-mass AGB stars by the 13C(α,n)16O reaction, requiring proton injection from the envelope. The 13C pocket was − typically assumed to involve a small mass (≤ 10 3 M ), but models with rotation sug- gest that 14N hampers s-processing in such tiny layers. Recent spectroscopy of young open clusters, showing enhancements of s-element abundances with respect to the Sun, suggest more effective s-process production requiring 13C-rich layers extended in mass − (≥ 4×10 3 M ). We speculated that mixing driven by magnetic buoyancy (or other forced mechanisms ”from bottom to top”) can form a 13C reservoir larger than assumed so far, covering most of the He-rich layers. We present new calculations aiming at understand- ing if the solar composition helps to constrain the 13C pocket extension. Stellar models at a fixed metallicity, based on a large 13C reservoir reproduce the main s-component as accurately as before and they don’t require any nuclear contribution from any unknown nucleosynthesis processes (LEPP). These models also avoid problems of mixing at the envelope border and fulfil requirements from C-star luminosities. A large production of nuclei below A = 100 is expected, so that 86, 87Sr may be fully synthesized by AGB stars, while 88Sr, 89Y and 94Zr are contributed more efficiently than before. We finally suggest tests that could provide more strict constraints for the extension of the 13C pocket.

45 The challenges of abundance analysis for long period variables

T. Lebzelter, W. Nowotny, K.H. Hinkle, S. Höfner, B. Aringer

Asymptotic giant branch (AGB) stars play a key role for the enrichment of galaxies with heavy elements. Due to their large amplitude variability, the measurement of elemental abundances is a highly challenging task that has not been solved in a satisfactory way yet. We used hydrostatic and dynamical model atmospheres to simulate observed high- resolution near-infrared spectra of 12 variable and non-variable red giants in the globular cluster 47 Tuc. The 47 Tuc red giants are independently well-characterized in important parameters (mass, metallicity, luminosity). The principal aim was to confront synthetic spectra based on the dynamical models with observational spectra of 47 Tuc variables. Assuming that the abundances are unchanged on the upper giant branch in these low- mass stars, our goal is to estimate the impact of atmospheric dynamics on the abundance determination. Our study includes lines of 12CO, 13CO, OH, and Na.

46 Nucleosynthesis in AGB stars traced by isotopic ratios

R. De Nutte, L. Decin, A. de Koter

Isotopic ratios are by far the best diagnostic tracers of the stellar origin of elements, as they are very sensitive to the precise conditions in the nuclear burning regions. They al- low us to give direct constraints on stellar evolution models and on the progenitor mass, and can be used to check the origin of presolar grains. These grains are thought to retain the isotopic compositions of the stellar gases from which they condensed, but their com- position also reflects the complex interplay of galactic chemical evolution and the physic- ochemical conditions during dust formation. However, up to now different isotopic ratios have been well constrained only for a handful of asymptotic giant branch (AGB) stars. Furthermore, these ratios have been found to differ significantly from data obtained from presolar grains. We present new data on isotopologue lines of a well-selected sample of AGB stars, covering the three spectral types of C-, S- and M-type stars. We report on the first modelling efforts made in determining accurate isotopologue fractions, focus- ing on C- and O-isotopes, with the latter being a crucial tracer of the poorly constrained extra-mixing processes in stellar atmospheres.

47 The 12CO/13CO-ratio in AGB stars of different chemical type

H. Olofsson, S. Ramstedt

We have investigated the evolution of the 12C/13C-ratio along the AGB through the cir- cumstellar isotopologue 12CO/13CO abundance ratio. Our sample includes a significant number of M- and S-type AGB stars and carbon stars. This makes it possible to inves- tigate trends among the different types and establish evolutionary effects. The circum- stellar 12CO/13CO abundance ratios are estimated through a detailed radiative trans- fer analysis of single-dish radio line emission observations. Several different transitions have been observed for each source to ensure that a large part of the circumstellar en- velope is probed and the radiative transfer model is well-constrained. The circumstellar 12CO/13CO abundance ratio differs between the three spectral types. This is consistent with what is expected from stellar evolutionary models assuming that the spectral types constitute an evolutionary sequence, however, this is the first time this has been shown observationally for a relatively large sample covering all three spectral types. The me- dian value of the 12CO/13CO abundance ratio in the inner circumstellar envelope is 13, 26, and 34 for the M-type, S-type and carbon stars, respectively. The abundance ratio spread of the carbon stars is much larger than for the M- and S-type stars, also when excluding J-type carbon stars, in line with what could be expected from evolution on the AGB. We find no correlation between the isotopologue ratio and the mass-loss rate, as would be expected if both increase as the star evolves.

48 The dust return from AGB stars in nearby galaxies

S. Srinivasan Invited

AGB stars lose a substantial fraction of their mass in slow, dust-driven winds. This mass loss directly influences the life cycle of dust and gas in galaxies. The dust consists of ei- ther oxygen-rich or carbonaceous particles, depending on the relative atomic abundance of carbon to oxygen (the C/O ratio) in the photospheric regions. Determining the current rate of AGB dust production requires information about the spec- tral energy distributions (SEDs), especially in the infrared. While large-scale studies of the Galactic AGB dust budget have been restricted to the Bulge or the Solar Neighbourhood, data from the Spitzer Space Telescope has enabled the identification of large populations of AGB stars in nearby galaxies such as the Magellanic Clouds, allowing us to estimate the current AGB dust budget in these systems. These studies find that the dust produc- tion is dominated by a small fraction of very dusty, highly evolved AGB stars. However, the dust injection rates estimated for these systems is too small to explain the observed masses of interstellar dust. In this talk, I will review the theoretical and observational constraints on AGB dust pro- duction in nearby galaxies and discuss possible solutions to the dust budget "crisis".

49 Session 4: Old & new dust

Dust formation in AGB stars

I. Cherchneff Invited

The booklet was faster than this abstract.

50 Dust formation in the inner wind of the oxygen-rich AGB star IK Tau

D. Gobrecht, I. Cherchneff, A. Sarangi

The purpose of the study is to understand the formation processes underpinning the for- mation of dust in oxygen-rich AGB stars, reproduce molecular abundances in the dust formation zone, and derive dust mass yields for specific condensates. We model the inner wind of the O-rich Mira, IK Tau, by considering layers of gas above the stellar pho- tosphere that are periodically crossed by pulsation-induced shocks. These gas layers experience a wide range of temperatures and number densities and are still gravitation- ally bound to the star. The formation of molecules and dust clusters follows a chemical kinetic approach, and is described by a chemical network, which includes the formation pathways to small clusters of silicates (e.g., enstatite, MgSiO3, and forsterite Mg2SiO4), clusters of alumina (Al2O3), and metal oxides. The dust nucleation phase is then cou- pled to the condensation phase, described by a Brownian formalism, to derive grain size distributions and mass yields. Our results for molecules (CO, H2O, SiO, SO, CO2, SiS, PN) agree well with the most recent observations with Herschel, and confirm the crucial role of shocks in the making of carbon-rich molecules, such as HCN, CO2 and CS, in O-rich AGB inner winds. The nucleation of small silicate grains of forsterite stoichiom- etry proceeds through a new chemical route involving the dimerization of HSiO. These clusters grow and condense around 4 R?. They keep growing over several pulsation periods and shock passages as the gas layers move to larger radii. At 5 R?, 65 % of silicate clusters condense into grains of average radius 40 Å, while at 8 R?, 95 % of all silicate clusters have condensed to form small grains with average radius ∼ 100 Å. Our − final dust-to-gas mass ratio for silicates is ∼ 2 × 10 4, and in good agreement with values − characteristic of O-rich AGB stars (10 3). Our results indicate that the wind acceleration due to silicate grains will take place at radii larger than 5 R?, in good agreement with recent observations of CO and HCN emission lines.

51 Interferometric constraints on molecule and dust formation in oxygen-rich Mira stars

M. Wittkowski, I. Karovicova, M. Scholz, K. Ohnaka, D. A. Boboltz

We present new results from our project of spatially and spectrally resolved multi-epoch near- and mid-infrared interferometric observations of oxygen-rich Mira stars using the ESO VLT Interferometer (VLTI). We aim at constraining the structure of the molecular atmosphere and of the inner region of the dust shell, and ultimately at understanding the formation of molecules and dust grains and their subsequent expulsion into the interstel- lar medium. We compare our near-infrared data with the recent CODEX dynamic model atmospheres, and the mid-infrared data with radiative transfer models of the dust shell, where the central source is described by dynamic model atmospheres. We confirm that the near-IR data are well described by the CODEX models including features of extended water vapor and CO layers. Our mid-infrared data are consistent with Al2O3 grains con- densing close to the photosphere at about 2 stellar radii and warm silicates condensing at about 4-5 stellar radii. We confirm that the number density of aluminum can match that of the best-fit dust shells near the inner dust shell radius up to the condensation radii of warm silicates, confirming that Al2O3 grains can be seed particles for the further dust condensation.

52 Wind acceleration in AGB stars: Solid ground and loose ends

S. Höfner Invited

The winds of cool luminous AGB stars are commonly assumed to be driven by radiative pressure on dust grains, forming in the extended dynamical atmospheres which are a result of pulsation-induced shocks. This pulsation-enhanced dust-driven wind scenario has passed a range of critical observational tests as models have developed from empir- ical and qualitative to more self-consistent and quantitative. However, when compared with the complex reality of AGB stars, even state-of-the-art models are still simplistic and incomplete in certain respects, reflecting both a lack of computing power and gaps in our knowledge. In this talk, I will discuss the current understanding of wind acceleration, and outline areas where further efforts by theorists and observers are needed to develop reliable quantitative models of mass loss for cool giants.

53 Exploring mass-loss in M-type AGB stars

S. Bladh

The wind mechanism behind the observed mass loss in M-type AGB stars is a long- standing problem in AGB research. It has been debated if these winds are dust-driven, as seems to be the case for C-type AGB stars, or if other physical processes are at play. The critical points for a dust-driven wind scenario are grain materials that is thermally sta- ble close to the star and can produce enough momentum transfer to trigger outflows. We will give a progress report on our dynamical models for M-type AGB stars where stellar winds are driven by radiation pressure due to scattering on large Fe-free silicate grains. We will present new dynamical and photometric results from a substantial grid of models and how they compare to observations. The grid includes different combinations of fun- damental stellar parameters such as luminosity, mass and effective temperature, but also parameters such as pulsation period, pulsation amplitude and seed particle abundance.

54 Amorphous aluminum oxide grains as the wind drivers in W Hya

T. Khouri, R. Waters, A. de Koter, M. Min, L. Decin, R. Lombaert

Low- and intermediate-mass stars are thought to eject a significant fraction of their en- velopes during the asymptotic giant branch (AGB) phase. The wind is thought to be driven by radiation pressure acting on dust grains, that form due to the large scale-height and low temperatures of the atmospheres of these stars. For oxygen-rich AGB stars, it was not clear which dust species provides the required opacity, because highly absorbing ma- terials cannot exist close enough to the star to drive the wind. Recently, it was suggested that the transfer of momentum between the radiation field and grains happens through scattering of photons rather than absorption. However, this qualitative picture is not yet completely understood and the nature of the dust grains responsible for driving the wind is still debated. Due to our lack of understanding of the wind driving mechanism, predict- ing the mass-loss evolution of a given AGB star is also not possible presently. In order to address this from an observational point of view, we have studied the wind of W Hya, a close-by oxygen-rich AGB star. The molecular gas and dust envelope of W Hya have both been extensively observed with different techniques and instruments. This wealth of observations allows one to obtain a very detailed model of its wind. We study the wind-driving mechanism by confronting gas and dust wind models and by tracing the abundances of the dust forming elements in these two phases. We find strong evidence that amorphous aluminum oxide grains are responsible for driving the wind of W Hya. Silicate emission arises only from an envelope with inner radius of 50 AU, a region where the wind also seems to receive an extra injection of momentum.

55 The problematically short superwind of OH/IR stars - Probing the outflow with the 69 micrometer spectral band of forsterite

B.L. de Vries

Spectra of OH/IR stars show prominent spectral bands of crystalline olivine (Mg(2−2x)Fe(2x)SiO4). To learn more about the timescale of the outflows of OH/IR stars, we studied the spectral band of crystalline olivine at 69 micrometer. The 69 microme- ter band is of interest because its width and peak wavelength position are sensitive to the grain temperature and to the exact composition of the crystalline olivine. With Her- schel/PACS, we observed the 69 micrometer band in the outflow of 14 OH/IR stars. By comparing the crystalline olivine features of our sample with those of model spectra, we determined the size of the outflow and its crystalline olivine abundance. The temperature indicated by the observed 69 micrometer bands can only be reproduced by models with a geometrically compact superwind (Rsw < 2500 AU = 1400 R?). This means that the su- perwind started less than 1200 years ago (assuming an outflow velocity of 10 km/s). The small amount of mass lost in one superwind and the high progenitor mass of the OH/IR stars introduce a mass loss and thus evolutionary problem for these objects, which has not yet been understood.

56 Dust production from sub-solar to super-solar metallicity in Thermally Pulsing Asymptotic Giant Branch Stars

A. Nanni, A. Bressan, P. Marigo, L. Girardi, A. Javadi, J. Th. van Loon

We discuss the dust chemistry and growth in the circumstellar envelopes (CSEs) of Ther- mally Pulsing Asymptotic Giant Branch (TP-AGB) star models computed with the COL- IBRI code, at varying initial mass and metallicity (Z = 0.001, 0.008, 0.02, 0.04, 0.06). We provide new important diagnostic tools useful to calibrate the properties of TP-AGB stars during this complex phase of stellar evolution. A relevant result of our analysis deals with the silicate production in M-stars. We show that, in order to reproduce the observed trend between terminal velocities and mass-loss rates in Galactic M-giants, one has to signif- icantly reduce the efficiency of chemisputtering by H2 molecules, usually considered as the most effective dust destruction mechanism. This indication is also in agreement with the most recent laboratory results, which show that silicates may condense already at Tcond ∼ 1400 K, instead than at Tcond ∼ 1000 K, as obtained by models that include chemisputtering. From the analysis of the total dust ejecta, we find that the total dust- to-gas ejecta of intermediate-mass stars are much less dependent on metallicity than usually assumed. In a broader context, our results are suitable to study the dust enrich- ment of the interstellar medium provided by AGB stars in both nearby and high redshift galaxies.

57 EvolutioN of Grains in the MAgellanic clouds (ENiGMA)

M. Meixner, K. Tschernyshyov, E. Dwek, T. Temim, M. Boyer, C. Gall, R. Eufrasio

We present preliminary results from our dust evolution modeling of the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC). Despite the many manifestations of dust in galaxies, its nature, origin, and evolution are still poorly understood. The LMC and SMC are ideal astrophysical laboratories to study the lifecycle of dust in galaxies, because all stars and ISM clouds are at a similar distance, rendering masses and luminosities directly comparable. Moreover, their proximity permits detailed studies of the stars and their relation to the ISM dust from local to galaxy wide scales. Their sub-solar metallicities permit investigations on how dust evolution depends on metallicity. Using the results from the Spitzer Surveying the Agents of Galaxy Evolution (SAGE) surveys and HERschel Inventory of The Agents of Galaxy Evolution (HERITAGE) surveys of the LMC and SMC, we can quantify some key aspects of the dust lifecycle in these galaxies. In particular, the infrared and submillimeter emissions are effective tracers of the interstellar medium (ISM) dust, the embedded young stellar objects (YSOs) and the dust ejected by dying stars. We use the theoretical framework developed in Dwek (1998) to develop the dust evolution models. We have further constraints from prior work on the star formation histories, stellar content and metal abundance measurements. In this presentation, we will discuss the dust production of asymptotic giant branch stars and their importance in the dust evolution of the Magellanic Clouds, which have a rich assortment of constraints.

58 Dust in the early universe and the contribution of AGB stars

R. Schneider Invited

Observations of quasars at z> 6 at millimeter wavelengths have provided irrefutable evidence of the existence of dust masses in excess of 108 M in their host galaxies. The origin of these huge dust masses, which have to be produced in less than 1 Gyr since the Big Bang, is still a challenge to theoretical models. Yet, it shows that early star formation in the universe leads to rapid enrichment of the interstellar gas with metals and dust, which change the cooling and fragmentation properties of star forming clouds, ultimately affecting the initial mass function of second generation stars. The question is then, what are the first sources of dust? On the one hand, Herschel observations have proved that dust can efficiently form in supernova ejecta, with masses [0.06−0.5] M . Yet, none of the remnants is old enough for the reverse shock to have significantly affected the newly formed dust, and the effective mass that will survive enriching the interstellar medium may be significantly smaller. On the other hand, AGB stars are considered a major dust producer in the present-day universe. However, their role in dust enrichment in the early universe crucially depends on the stellar initial mass function of the first stellar generations, on the star formation history, and on the mass and metallicity dependence of the dust yields. In this talk, I will review the role of AGB stars in early dust enrichment in light of new theoretical dust yields for stars with mass 1 M < m? < 8 M and metallicity 0.0003 < Z < 0.018, obtained with models that follow stellar evolution from the pre-main sequence phase until the almost complete ejection of the stellar mantle. The models have been shown to reproduce the measured dust production rates by carbon-rich and oxygen- rich AGB stars in the Small and Large Magellanic Clouds, and the observed colors of the so-called extreme stars in the LMC. I will discuss the relative role of AGB stars and SNe in early dust enrichment and the impact of these two classes of stellar sources on the nature and composition of the first dust. Finally, using semi-analytical models for the coevolution of the nuclear black holes and the host galaxies in a cosmological context, I will assess whether the observed dust masses in z > 6 quasars can be of stellar origin or if alternative dust production mechanisms must be invoked.

59 Metallicity dependence of oxygen-rich dust around evolved stars

O. Jones, C. Kemper, S. Srinivasan, I. McDonald, G. Sloan, A. Zijlstra

Observations of evolved stars in Local Group galaxies show that metallicity has a signifi- cant influence on the production and chemical composition of dust. In order to determine the composition of the dust in the circumstellar envelopes of oxygen-rich AGB stars, we have computed a grid of MODUST radiative-transfer models for a range of dust com- positions, mass-loss rates, dust-shell inner radii and stellar parameters. We use these models to fit a sample of 37 O-rich AGB stars in the LMC with optically thin circumstellar envelopes, for which 5-35 micron Spitzer infrared spectrograph spectra and broad-band photometry from the optical to the mid-infrared are available. From the modelling, we find − − mass-loss rates in the range ∼ 8 x 10 8 to 5 x 10 6 M /yr, and we show that a grain mixture consisting primarily of amorphous silicates, with contributions from amorphous alumina and metallic iron, provides a good fit to the observed spectra. We will relate these recent results to other works at varying metallicity and discuss the dust input into the ISM by oxygen-rich stars as the universe evolves.

60 How important are metal-poor AGB stars as cosmic dust producers?

L. Mattsson, B. Aringer, S. Höfner, K. Eriksson, A. Andersen

The efficiency of dust formation in AGB stars seems to be metallicity dependent. Oxygen- rich AGB stars should (in theory) have to have a certain metallicity since they are not pro- ducing their own raw material for dust production and metal-poor carbon stars may not be very efficient dust producers either, because of more radiative heating of the grains forming in their atmospheres. We have just confirmed that inefficient dust and wind for- mation in simulations of very metal-poor (1/100 of solar metallicity) carbon stars is a real physical effect, albeit within the limitations of our simulations, and not a numerical issue (as we first thought). Taken at face value, this implies that the amount of dust supplied by early low-metallicity AGB stars to the build up of the cosmic dust component is clearly limited. Consequently, one may also ask how large a contribution AGB stars can make in general when compared to recent observations of cosmic dust, which are suggesting major contributions from other sources?

61 Session 5: Resolved and unresolved Populations

Nucleosynthesis in Helium-enriched AGB models: Implications for Globular Clusters

A. I. Karakas, L. Shingles, A. F. Marino, D. M. Nataf

We investigate the effect of helium enrichment on the evolution and nucleosynthesis of asymptotic giant branch (AGB) stars with a metallicity of Z = 0.0006 ([Fe/H] = –1.4). We calculate evolutionary sequences with the primordial helium abundance (Y = 0.24) and with helium-enriched compositions (Y = 0.30, 0.35, 0.40). Post-processing nucleosyn- thesis calculations are performed on each of the evolutionary sequences to determine the production of elements from hydrogen through to bismuth. Elemental surface abundance predictions and stellar yields are presented for each model. The models with enriched helium have shorter main sequence and AGB lifetimes, and enter the AGB with a more massive hydrogen exhausted core than the primordial helium model. The main conse- quences are 1) AGB models with enhanced helium will evolve more than twice as fast, giving them the chance to contribute sooner to the chemical evolution of the forming glob- ular clusters, and 2) the stellar yields will be strongly reduced relative to their primordial helium counterparts. In the low-mass AGB models we find that an increase of ∆Y = 0.10 at a given mass decreases the yields of carbon by up to about 60%, of fluorine by up to 80%, and decreases the yields of the s-process elements barium and lanthanum by about 50%. While the yields of first s-process peak elements strontium, yttrium and zir- conium decrease by up to 50%, the yields of rubidium either do not change or increase.

62 Results from the PHAT project

L. Girardi Invited

The Panchromatic Hubble Andromeda Treasury (PHAT) is an HST multi-cycle treasury program that mapped 1/3 of M31 from the UV through the near-IR. It provides photom- etry in up to 6 filters for about 117 million stars distributed across ∼ 20 kpc of the M31 disk, with a spatial resolution comparable to the one routinely attained for the Magel- lanic Clouds from the ground. The survey is complemented by the Spectroscopic and Photometric Landscape of Andromeda’s Stellar Halo (SPLASH) survey, which provides Keck/DEIMOS spectra for thousands of the brightest targets. I will start presenting an overview of the data, and how they are revolutionizing our view of the spatial distribution of stars and dust across M31. Then, I will describe several results related to the topic of this meeting: 1) the overall spatial distribution of AGB stars as compared to the RGB; 2) the unusual populations of UV-bright stars in the M31 bulge; 3) the improved view of the PNe population; 4) the detection of a dramatic drop in the C/M ratio towards the inner M31 disk; 5) the correlation between AGB properties and the star formation histories de- rived for some of the less-crowded and less-extincted fields; and 6) their contribution to the integrated mid-infrared fluxes. These rich datasets will allow us to test the evolution of AGB stars in a metal-rich and star-forming environment, avoiding the incompleteness and distance uncertainties that severely limit similar studies in the Milky Way.

63 Constraining Mass Loss & Lifetimes of Low Mass, Low Metallicity AGB Stars

P. Rosenfield, P. Marigo, L. Girardi, J. J. Dalcanton, A. Bressan, M. Gullieuszik, D. Weisz, B. F. Williams, A. Dolphin, B. Aringer

The evolution and lifetimes of thermally pulsating asymptotic giant branch (TP-AGB) stars suffer from significant uncertainties. I present analysis of the numbers and luminosity functions of TP-AGB stars in six quiescent, low metallicity ([Fe/H] . –1.2) galaxies taken from the ANGST sample, using HST photometry in both optical and near-infrared filters. The galaxies contain over 1000 TP-AGB stars (at least 60 per field). We compare the observed TP-AGB luminosity functions and relative numbers of TP-AGB and RGB stars to models generated from different suites of TP-AGB evolutionary tracks after adopting star formation histories derived from the HST deep optical observations. We test various mass-loss prescriptions that differ in their treatments of mass loss before the onset of dust-driven winds (pre-dust). These comparisons confirm that pre-dust driven mass loss is important, since models that neglect pre-dust mass loss fail to explain the observed NTP-AGB/NRGB ratio or the luminosity functions. In contrast, models with more efficient pre-dust driven mass loss produce results consistent with observations. We find that for [Fe/H] . –1.2, lower mass TP-AGB stars (M . 1 M ) must have lifetimes less than about 1.2 Myr. In addition, we show that the third dredge up has no significant effect on TP-AGB lifetimes in this mass and metallicity range.

64 The photometric and stellar properties of carbon stars in the Small Magellanic Cloud

G. C. Sloan

Combining data from optical monitoring programs and near- and mid-infrared surveys of the Small Magellanic Cloud has improved our understanding of how carbon stars shed their envelopes and make dust. And yet more work is needed. One challenge is the determination of bolometric magnitudes, which are essential for comparisons to evolu- tionary models. The traditional approach using bolometric corrections for near-infrared photometry gives results for the most embedded sources which are inconsistent with the period-luminosity relation for Miras. The stars could have evolved beyond the P-L rela- tion, they could have asymmetric dust shells, or most likely, the bolometric corrections are breaking down for the reddest sources. Applying radiative transfer models and fitting spectral templates to the photometry support this last possibility, but work is ongoing. Over half of the stars identified in the OGLE-III survey as semi-regular variables (SRVs) are actually pulsating in the fundamental mode, like Mira variables. The [5.8]−[8] and J-K colors, which probe the molecular bands and dust extinction in the envelope, pro- vide an alternative to the amplitude-based distinction between SRV and Mira and better identify the fundamental-mode pulsators producing dust. The optical monitoring surveys are biased against embedded carbon stars, hiding from our view those stars currently producing the most dust. A solution is to search for variables in the longer-wavelength surveys, although these suffer from more limited temporal sampling. Addressing all of these issues is helping to disentangle how pulsations and radiation pressure on forming dust drive the mass-loss process that ends the lives of these stars.

65 Post-AGB stars in the Magellanic Clouds

D. Kamath, P. Wood, H. Van Winckel

The late stages of evolution for low- to intermediate-mass single stars is a rapid transition from the Asymptotic Giant Branch (AGB) phase through the transient post-AGB phase and towards the Planetary Nebula Phase (PNe) before the stellar remnant cools down as a White Dwarf (WD). Although this evolution scheme seems straight forward, there is little understanding from first principles of the different important physical processes that govern these evolutionary phases. Though a large sample of Galactic post-AGB stars have been observed, the major obstacle to exploiting our existing and growing sample of observed Galactic evolved stars is that the distances (hence luminosities and radii) are poorly determined. In our recent studies, we exploited the release of the infrared LMC and SMC SAGE-Spitzer survey to identify optically bright evolved stars with infrared colours indicative of a past history of heavy dusty mass loss in the LMC and SMC. Realising the importance of the spectral characterisation of the central objects to confirm their post- AGB nature, we performed an extensive low resolution optical spectral survey with the AAOmega multi-fibre spectrograph with a 2 degree field of view. We obtained around 3000 spectra of evolved objects in the LMC and around 1000 spectra in the SMC. During our spectroscopic characterisation of the post-AGB stars we removed all likely contami- nating sources either on the basis of their optical spectra, or in more complicated cases, such as young stellar (YSOs) objects, we devised a robust criterion to remove YSOs based on the derived surface gravity (log g) values. Our spectral analysis therefore re- sulted in a clean and complete census of well characterised post-AGB objects (single and binary stars) with spectroscopically determined stellar parameters (Teff, log g, [Fe/H] and E[B-V]) spanning a wide range in luminosities in the LMC and SMC. We also found a significant sample of post-RGB stars in the LMC and SMC. In this talk, I will present an overview of this survey, the final catalogue of post-AGB/RGB stars in the Magellanic Clouds, and other outcomes of this survey. I will also discuss ways in which these objects can serve as ideal traces of single and binary evolution, AGB nucleosynthesis, etc.

66 Presenting Optical Spectra of AGB Stars in M31

K. Hamren, R. GuhaThakurta, E. Toloba, C. Dorman, A. Seth, L. Prichard; SPLASH Collaboration; PHAT Collaboration

We present optical spectra of AGB stars in the disk, halo and satellite galaxies of An- dromeda (M31), including spectroscopically identified O- and C-rich giants and stars with Hα emission. The AGB sample is drawn from a sample of ∼ 34, 000 stars for which we have Keck II/DEIMOS spectra. In addition to moderate-resolution spectroscopy, we have 0 0 optical (g +i or M + T2) photometry from the Spectroscopic and Photometric Landscape of Andromeda’s Stellar Halo (SPLASH) survey the M31 halo and satellite members of our sample. Near-IR photometry (J and K) is currently being obtained by the M31 Asymp- totic Giants Extended Survey (M31AGES). We have six filter photometry spanning the UV to the near-IR (F275W, F336W, F475W, F814W, F110W, F160W) from the Panchro- matic Hubble Andromeda Treasury survey (PHAT) for the disk members of our sample. We discuss spectral trends as a function of color, magnitude and location, and present the kinematics and spatial distribution of the AGB sample with respect to the non-AGB populations.

67 AGB populations of LG dwarf spheroidals

J. Menzies Invited

Dwarf galaxies in the Local Group constitute a good representation of dwarfs outside its border in the nearby Universe. In the near infrared most of the brightest stars in these galaxies are on the AGB and can be studied in some detail on an individual basis. This allows for tests of models of the late stages of stellar evolution, as well as providing information on the star formation history in the parent galaxies. Some AGB stars are Mira variables, for which an infrared period-luminosity relation exists, though distance estimation is not entirely straightforward thanks to the reddening produced by copious mass loss from some of these stars. This review will focus on our current understanding of the photometric characteristics of AGB stars in the Local Group and of prospects for discovery as investigations push well beyond its boundary in the near future.

68 An Infrared Census of Extreme AGB Stars in Nearby Dwarf Galaxies

M. Boyer, K. McQuinn, P. Barmby, A. Bonanos, R. Gehrz, K. Gordon, M. Groenewe- gen, E. Lagadec, D. Lennon, M. Marengo, M. Meixner, E. Skillman, G. Sloan. J. Th. van Loon, A. Zijlstra

Nearby resolved dwarf galaxies provide excellent opportunities for studying the dust- producing late stages of stellar evolution. DUSTiNGS (DUST in Nearby Galaxies with Spitzer) is a 3.6- and 4.5-µm imaging survey of 50 dwarf galaxies (D < 2 Mpc) designed to identify dust-producing Asymptotic Giant Branch (AGB) stars. The DUSTiNGS survey includes a large sample of galaxies to build statistics on this short-lived phase of stel- lar evolution: 37 dwarf spheroidal, 8 dwarf irregular, and 5 transition-type galaxies. We obtained observations in two epochs, separated by approximately 6 months, to assist in identifying long-period thermally-pulsing (TP-)AGB stars. We find more than 500 dusty variable TP-AGB stars (sometimes called extreme AGB stars). The majority of these stars are new discoveries, including dozens located in the quiescent dwarf spheroidal galaxies. These stars are likely in the superwind phase and thus dominate the current dust input to the interstellar medium of their respective galaxies.

69 Model constraints from observations of active galaxies

R. Riffel Invited

Studying the unresolved stellar content of galaxies generally involves disentangling the various components contributing to the spectral energy distribution (SED), fitting a com- bination of simple stellar populations (SSPs) to derive information about age, metallicity, and star formation history. In the near-infrared (NIR, 0.85-2.5 µm), the thermally pulsing asymptotic giant branch (TP-AGB) phase – the last stage of the evolution of intermediate mass stars (M . 6 M ) – is a particularly important component of the SSP models. These stars may be able to dominate the emission of stellar populations with ages ∼ 0.2−2 Gyr being responsible for roughly half of the luminosity in the K-band. In addition, when trying to describe the continuum observed in active galactic nuclei, the signatures of the central engine and from the dusty torus cannot be ignored. Over the last years we developed a method to disentangle these three components. Our synthesis shows significant differ- ences between Seyferts 1 (Sy 1) and Seyferts 2 (Sy 2) galaxies: the hot dust component is required to fit the K-band spectra of ∼90% of the Sy 1 galaxies, and only of ∼25% of the Sy 2; about 50% of the Sy 2 galaxies require a FC component contribution & 20%, while this fraction increases to about 60% in the Sy 1; also, in about 50% of the Sy2, the combined FC and young components contribute with more than 20%, while this occurs in 90% of the Sy1, suggesting recent star formation in the central region. The central few hundred parsecs of our galaxy sample contain a substantial fraction of intermediate-age SPs with a mean metallicity near solar. Two-dimensional mapping of the near-infrared stellar population of the nuclear region of active galaxies suggests that there is a spatial correlation between the intermediate-age stellar population and a partial ring of low stellar velocity dispersion (σ?). Such age is consistent with a scenario in which the origin of the low-σ? rings is a past event which triggered an inflow of gas and formed stars which still keep the colder kinematics of the gas from which they have formed. Besides, we will also discuss the presence fingerprints of features attributed to TP-AGB stars in the spectra of the nuclear region of nearby galaxies.

70 Probing the Sagittarius Tidal Streams with LPV Carbon Stars

A. Huxor, E. Grebel

We have assembled a sample of ∼120 spectroscopically-confirmed carbon stars, from the literature, and which exhibit measurable variability in the 2nd Data Release of the Catalina Sky Surveys. Periods and amplitudes for this sample, are used to estimate dis- tances from period-luminosity relationships. The location of the carbon stars (and their velocities where available) allow us to trace the streams of the Sagittarius (Sgr) dwarf spheroidal galaxy. These are compared to the Law & Majewski (2010) numerical simula- tion of its ongoing accretion. We find that the data match the model well for heliocentric distances of 15 to 50 kpc, except for a lack of carbon stars in the trailing arm just above the Galactic Plane, and there is only tentative evidence of the leading arm south of the Plane. About half of the sample can be attributed to the Sgr accretion, others are likely associated with known MW halo substructures, while a dozen seem to have no obvious attribution - and may indicate new substructure. We find suggestions of distant structures at > 100 kpc, from a handful of AGB carbon stars which have good spectra and/or light curves. This work continues the tradition of using carbon stars as probes of the MW halo, indicating target regions for deep imaging. Such imaging may reveal new halo substruc- ture, aid revision of the computer model, and so throw new light on the evolution of our Galaxy.

71 Phase-lag distances of OH masing AGB stars

D. Engels, S. Etoka, E. Gerard

Distances to AGB stars with optically thick circumstellar shells cannot be determined us- ing optical parallaxes. However, for stars with OH 1612 MHz maser emission emanating from their circumstellar shells, distances can be determined by the phase-lag method. This method combines a linear diameter obtained from a phase-lag measurement with an angular diameter obtained from interferometry. The phase-lag of the variable emission from the back and front sides of the shells is determined for 20 OH/IR stars in the galactic disk. It is measured on the base of a monitoring program with the Nancay radio telescope ongoing for more than 6 years. Recent eMERLIN and eVLA observations of several stars provided angular diameters. The new distances for the sample will provide an improved estimate of the mass range from which these highly obscured stars descend from. I will discuss the new distances obtained and the uncertainties inherent in the method.

72 Session 6: Perspectives

Stellar astrophysics with the ELT

G. Bono Invited

The booklet was faster than this abstract.

73 Mid- and Far- InfraRed space prospects for research on AGB stars

J. Blommaert Invited

A lot of our present-day knowledge of AGB stars is based on observations performed in the infrared wavelength regime, in particular with space observatories. With the increas- ing sensitivity, angular resolution and improved spectral capabilities each new space mis- sion has contributed to the great progress made in the last decades. In this talk, I will present two future infrared space missions and discuss what prospects they can offer to AGB research. The first observatory is the James Webb Space Telescope, which will have a 6.5 m diameter primary mirror and is planned to be launched in 2018. In this presentation most attention will be given to MIRI, the mid-infrared instrument which provides direct imaging and medium resolution spectroscopy (R ∼ 3000) over the wave- length range 5 – 28.3 micron. MIRI also offers coronagraphic imaging and low resolution spectroscopic (R ∼ 100, over 5 – 10 micron) capabilities. The second mission is SPICA: "A Space Infrared Telescope for Cosmology and Astrophysics" which is at present in pro- posal phase. SPICA will offer a large (3-m class) cooled telescope (< 6 K) and foresees scientific instruments covering the 5 – 210 micron wavelength range.

74 E-ELT MIR and MATISSE prospects for AGB-stars

J. Hron, J. Blommaert, O. Chesneau, A. Chiavassa, L. Decin, T. Lebzelter, C. Pala- dini, H. van Winckel

We summarize the characteristics and status of the E-ELT MIR instrument and the VLTI second generation instrument MATISSE and present selected science cases in the field of AGB stars. Emphasis is given to the structure of molecular and dusty envelopes, dust mineralogy, isotopic abundances, gas enrichment of galaxies and circumstellar disks.

75 Exploring the contribution of AGB stars to the Galactic chemical inventory using isotopic ratios

A. Goswami

There are some uncertainties over the time at which the first intermediate and low-mass stars had reached the AGB phase and began to pollute their environments with the prod- ucts of nucleosynthesis. While some studies in literature indicate that enrichment from AGB stars set in at a time corresponding to −2.4 < [Fe/H] < −2.1, others suggest a time as early as [Fe/H] ∼ −2.75. We will discuss how the measurements of stellar iso- topic ratios can be used to explore the contribution of AGB stars to the Galactic chemical inventory. Upcoming large telescopes of 25 to 42m size equipped with high resolution spectrographs will provide the resolution and sensitivity required for measurements of iso- topic ratios that are more fundamental indicators of nucleosynthesis. These estimates, when available, will significantly improve our understanding of nuclear processes in vari- ous astrophysical sites, providing new constraint on the origins of heavy elements in the Galaxy that is still in controversy.

76 Prospects for research on AGB stars and RSGs with long baseline interferome- ters and adaptive optics

G. Perrin Invited

The understanding of AGB and red supergiant stars requires data provided by differ- ent techniques and at different wavelengths. Spectroscopy is known to be an extremely important tool for stellar studies. Simulations are also very efficient to understand the physics of these objects, predict observations and establish science cases. But evolved stars are so complex that spatial information is absolutely necessary to unveil the reality of these objects and to solve for some degeneracies. The atmosphere and photosphere of a few handfuls of the closest and brightest stars can be resolved by the largest telescopes equipped with adaptive optics. For these particular objects, extraordinary images of the regions just above the photosphere have been obtained. In the case of red supergiants, maps have provided possible hints about the origin of mass loss and its connection with surface inhomogeneities. In most cases, however, telescopes alone are not sufficient and long baseline interferometers are mandatory to obtain useful spatial information. Recent improvements have led to first images of a few evolved stars. This breakthrough opens the way to more systematic and recurrent studies of stellar surfaces with both temporal and spatial resolution. I will review some of the results obtained so far and show how they fit in the landscape of results on AGB and red supergiants. I will also give some prospects about the potential of future Extremely Large Telescopes for this field of research.

77 The ALMA view of evolved stars

M. Maercker Invited

The Atacama Large Millimeter/submillimeter Array (ALMA) is the largest telescope of its kind, providing the astronomical community with high-spatial resolution, high-sensitivity images between 84 GHz to 720 GHz. During plan- ning and construction of the array, the observatory promised to open a new window on how we observe and investigate the universe around us, and the expectations on how ALMA would affect our understanding of evolved stars were high. ALMA started operations in October 2011, and already with the first observations of an AGB star during Cycle 0, ALMA gave us a unique view of the circumstellar environment around the carbon star R Scl. I will review the capabilities of ALMA during the current early science operations and the specifications for full science, and the implications this has for re- search on evolved stars. I will present the first results on ALMA observations of evolved stars, including detached shells, isotope ratios and thermal pulses around R Scl, dust nucleation in IRC+10216, a disc around the post-AGB object the Red Rectangle, and observations of the Boomerang nebula - the coldest object in the universe.

78 Analytical models of stellar winds to interpret ALMA data

W. Homan, L. Decin, A. De Koter

Recently, observations of stellar winds have shown that these outflows might harbour structural complexities on macro- and microscales (like spirals, shells, clumps, ...). Here, we focus on spiral structures, with the aim to expand our understanding on the mani- festation of such structures in the (one- and three dimensional) observables of a stellar wind. For this we have developed fully parametrised analytical models. We demonstrate the impact of different input parameters on (sub-mm) intensity maps and line profiles. Additionally, we show how the assumption of a homogeneous outflow might result in a misinterpretation of molecular spectral line data. Furthermore, we show how different ALMA configurations impact the synthetic intensity maps of spiral strucutres. Finally, we model cycle 0 ALMA data of CW-Leo using above insights.

79 The Wind Acceleration Region of Betelgeuse: Resolved at Centimeter Wave- lengths

E. O’Gorman

The lack of spatially resolved observations at the scale of the stellar chromosphere and wind acceleration region has hampered our understanding of the mechanisms responsi- ble for mass-loss from massive evolved stars. This region, which lies within the first few stellar radii, has been identified as the most important spatial scale for studies of mass- loss mechanisms (Holzer & MacGregor, 1985). Thermal free-free centimeter emission observations directly probe these crucial spatial scales but until recently, obtaining suf- ficient resolution and sensitivity has been the major barrier. Here we present spatially resolved multi-epoch centimeter wavelength VLA plus Pie Town observations of the mas- sive evolved star, Betelgeuse - the star which subtends the largest angular diameter in the northern sky (apart from the Sun). We compare our results with existing VLA and (e-)MERLIN data and highlight current possibilities at centimeter wavelengths.

80 Poster Presentations

Posters are sorted first by session, then by surname.

Session 1: Complex Atmospheres

Brightness asymmetries of cool giants and supergiants measured with VLTI- AMBER

P. Cruzalebes, A. Jorissen, Y. Rabbia, A. Chiavassa, C. Paladini, S. Sacuto, C. Siopis, G. Sadowski, A. Spang, O. Chesneau S1-01

Departure for centrosymmetry is suspected to be the rule for evolved stars. We present the results of a long-term collaborative program spanning 5 years to observe some 20 giants and supergiants with VLTI-AMBER. Although the uv-plane coverage was not full enough to proceed to reliable image reconstruction, we nevertheless obtain evidence for global deviation from centrosymmetry, using a new parameter, called CSP and derived from the measured triple product integrated over the wavelength range. We observe that CSP increases along the evolutionary track on the asymptotic giant branch. The tendency of CSP to increase with the atmospheric pressure scale height supports the hypothesis that the observed deviations from centrosymmetry are somehow related to convective cells, whose size depends upon the atmospheric pressure scale height.

81 Water cooling in OH 30.1 –0.7: a case-study for OH/IR stars

T. Danilovich, K. Justtanont, H. Olofsson, M.J. Barlow, J. Blommaert, J. Cami, L. Decin, F. Kerschbaum, M. Matsuura, B. Swinyard, D. Teyssier, L.B.F.M. Waters, J. Yates S1-02

OH/IR stars are a class of asymptotic giant branch (AGB) stars which are presently un- dergoing intense mass-loss. They are oxygen-rich and are shrouded in a thick envelope of dust. They are thought to be one of the final stages of AGB star evolution. We have new Herschel spectral observations (from HIFI, PACS and SPIRE) covering primarily CO and H2O line emission. Using our newly updated radiative transfer codes we are working towards a consistent model for CO and H2O line emission, including a full complement of heating and cooling processes, most notably H2O line cooling. If successful, inclu- sion of full H2O line cooling in our radiative transfer modeling will lead to more accurate mass-loss rate estimates for these stars.

A new library of synthetic spectra and photometry for evolved C stars

K. Eriksson, W. Nowotny, S. Höfner, B. Aringer S1-03

The evolution and spectral properties of stars on the AGB are significantly affected by mass loss through dusty stellar winds. Dynamic atmosphere and wind models are an essential tool for studying these evolved stars, both individually and as members of stel- lar populations (to understand their contribution to the integrated light and the chemical evolution of galaxies). We have computed low-resolution spectra and photometry (in the wavelength range of 0.35-25 µm) for a grid of 540 dynamic models with stellar parame- ters typical of solar-metallicity C-type LPVs and with a range of pulsation amplitudes. The models cover the dynamic atmosphere and dusty outflow (if present), assuming spherical symmetry, and taking opacities of gas-phase species and dust grains consistently into account. Comparisons with various observed data in general show a quite satisfactory agreement. The models are made available to the community as an electronic database for use in various theoretical and observational studies.

82 Carbon stars from the X-shooter Spectral Library

A. Gonneau, A. Lancon, S. Trager, R. Peletier, Y. Chen, B. Aringer, W. Nowotny S1-04

Carbon stars play an important role in the chemical enrichment of galaxies with interme- diate age stellar populations. Moreover, they contribute significantly to the infrared light of those galaxies. Thus, they should be properly taken into account in Stellar Population Synthesis calculations. We make use of the X-shooter Spectral Library to study a sample of carbon stars in the Milky Way and the Magellanic Clouds, simultaneously in the vis- ible and near-infrared wavelength ranges. We compare our observations with a recent series of state-of-the-art theoretical spectra. The aims are to estimate the fundamental parameters and the evolutionary status of the observed stars, as well as to validate the models across the broad wavelength range of X-shooter (300-2400 nm). This will reduce the uncertainties associated with Carbon star spectral libraries in the modelling of galaxy spectra, which will allow more robust constraints on stellar populations in galaxies.

Kepler and the Long Period Variables

E. Hartig, J. Cash, K. H. Hinkle, T. Lebzelter, K. J. Mighell, D. K. Walter S1-05

High precision Kepler photometry is used to explore the details of AGB light curves. Since AGB variability has a typical time scale on order of a year we discuss at length the removal of long term trends and quarterly changes in Kepler data. Photometry for a small sample of nine SR AGB stars are examined using the 30 minute cadence over a period of 45 months. While undergoing long period variations of many magnitudes, the light curves are shown to be smooth at the millimagnitude level over much shorter time intervals. No flares or other rapid events were detected on the sub-day time scale. The shortest AGB period detected is on the order of 100 days. Most of the SR variables in our sample are shown to have multiple radial modes. This is always the first overtone typically combined with the fundamental. A second common characteristic of SR variables is shown to be the simultaneous excitation of multiple closely separated periods for the same overtone mode. Approximately half the sample had a much longer variation in the light curve, likely a long secondary period. The light curves were all well represented by a combination of sinusoids. However, the properties of the sinusoids are time variable with irregular variations present at low level. No non-radial pulsations were detected. It is argued that the long secondary period variation seen in many SR variables is intrinsic to the star and linked to multiple mode pulsation.

83 The dynamic atmospheres of Mira stars: comparing the CODEX models to PTI time series of TU Andromedae

M. Hillen, T. Verhoelst, P. Degroote, B. Acke, H. Van Winckel S1-06

In this work we wish to present our published evaluation of the effectiveness of the in 2011 released CODEX models in representing M-type Mira variable atmospheres. We present a high-precision interferometric K-band time series of TU And, consisting of 50 nights that cover 8 subsequent pulsation cycles. At each phase, the flux at 2.2 µm was obtained, along with the spectral shape and visibility points in 5 channels across the K- band. We compared the data to the relevant dynamical, self-excited CODEX models. Both spectrum and visibilities are consistently reproduced at visual minimum phases. Near maximum, the current models predict a too compact and hot photosphere, and an extended atmosphere that lacks H2O opacity, compared to our observations. A better coverage in the model parameter space is needed to make firm conclusions on the cause of the discrepancies. For TU And, the discrepancy might be lifted by adopting a lower value of the mixing length parameter combined with an increased stellar mass and/or a decreased metallicity.

The multi-scale environment of RS Cnc from CO and HI observations

D. T. Hoai, L. D. Matthews, J. M. Winters, P. T. Nhung , E. Gérard , Y. Libert, T. Le Bertre S1-07

We present a detailed study of the circumstellar gas distribution and kinematics of the 00 semi-regular variable star RS Cnc on spatial scales ranging from ∼ 1 (∼ 150 AU) to 0 00 ∼ 6 (∼ 0.25 pc). The close environment of RS Cnc (from 1 to 20 ) can be described with a model in which the density and the velocity vary smoothly from the equatorial plane to the polar axis. In this model the mass loss rate is higher along the polar directions than in the equatorial plane, which seems to exclude both stellar rotation and magnetic field as a cause of the axi-symmetry. Outside this region, whose study is limited by the photo-dissociation of CO, HI data at 21 cm show that the flow is slowed down at a typical 0 distance of 1 (∼ 0.04 pc). Further away the flow is distorted by the relative motion of the 0 star with respect to the interstellar medium (1 to 6 , or 0.05 to 0.25 pc).

84 The close environment of TX Psc as seen with spectro-astrometry

J. Hron, T. Lebzelter, C. Paladini, S. Uttenthaler S1-08

In the course of an exploratory observing campaign, we obtained spectro-astrometric data for a few AGB-stars in the K, L and M-bands with CRIRES. In this poster, we con- centrate on the "normal" carbon star TX Psc for which we have M-band data from 2010 and 2013. We present the evidence for a blob like structure at a few stellar radii and the differences between the two observing epochs. We also discuss the potential of this method for AGB stars.

Oxygen-rich stellar mass loss: characterizing shocks

E. M. L. Humphreys, P. Bergman S1-09

The mass loss mechanism for oxygen-rich evolved stars remains a matter of debate, however it seems likely that stellar pulsation-driven shocks play a role in levitating dense material out to larger radii where it cools and condenses to form dust. Further obser- vational characterisation of the shocks is highly desirable. What is needed are some strong tracers of the inner envelope that can be used to deduce the radial extent for which the shocks will strongly affect circumstellar conditions and dynamics i.e. before they damp down further away in the circumstellar envelope (CSE; > 5R?). SiO masers have been used to some extent for this purpose, however an issue for using SiO masers to characterise shocks is that the predominant pump mechanism for these masers re- mains contested. To this end, in May 2013 we started a survey of 437, 439, 471 and 475 GHz water masers towards several evolved stars. We report on preliminary results here.

85 Tracing the clumpy shells of IRC+10216 with the JVLA

D. Keller, K. M. Menten, T. Kaminski S1-10

Carbon-bearing molecules in the circumstellar envelope (CSE) of the prototypical carbon- rich AGB-star IRC+10216 are distributed in clumpy shells similar to the dust which in- dicates a gas-dust coupling. It is not well understood to what extent these density- enhanced shells influence the chemistry of carbon molecules in carbon-rich CSEs in gen- eral. Chemical models and observations are inconsistent. Observing many molecules at multiple transitions improves our understanding of the chemical network, the influence of shocks and UV radiation and constrains the structure and dynamics in CSEs. We have obtained a new key dataset using the expanded Jansky Very Large Array. It consists of a spectral and imaging survey of IRC+10216 which covers 18-45 GHz with a sensitivity 00 on a mJy level and a resolution of 1 . This survey traces the molecular distribution in un- precedented detail and strongly constrains the chemistry in these clumpy shells. So far line emission from over 15 species has been identified and imaged, for several lines from different energy levels, isotopologues and vibrationally excited states. We will present our new dataset and highlight first results important for understanding the chemistry and origin of shells around AGB-stars.

Atmospheres, magnetism and mass loss of red supergiant stars

E. Josselin, J. Lambert, N. Ryde, M. Auriere, P. Petit S1-11

Red supergiant stars (RSG) are not only a a key evolutionary stage of massive stars, participating in the chemical evolution of galaxies. They also represent a fantastic ... and challenging laboratory of (magneto-)hydrodynamics. We will present recent results and on-going research on mass loss, atmospheres, and polarimetric studies of RSG that reveal a magnetic field of unknown origin. We discuss the interplay between these different processes.

86 NLTE effects in molecular spectra of cool evolved stars

J. Lambert S1-12

The interpretation of molecular spectra from cool (super-)giant stars is a long standing problem. In particular, the near infrared spectra obtained with ISO in the 2000’s have lead to the introduction of the new concept of MOLspheres (quasi-static layers of molecules above the photospheres), which is still debated. In this context, we developed a new method to solve the radiative transfer equation, without assuming Local Thermodynam- ical Equilibrium (LTE). This method is optimized to deal with large-scale systems such as molecules. It is now implemented in a fully parallelized (MPI) code named MOrad. Thanks to the recent availability of accurate collisional rates for H2O and CO, the two major molecules seen in infrared spectra of evolved cool stars, we are now able to tackle with the interpretation of new high resolution spectra and propose a new interpretation to the discrepancy which lead to the introduction of MOLspheres. We will present this new methodology and the resulting interpretation of H2O and CO spectra of red (super-)giant stars.

Winds of AGB stars - the role of stellar pulsation

S. Liljegren S1-13

Winds of AGB stars are presumably driven by a combination of pulsation-induced shock- waves and radiation pressure on dust. While considerable theoretical effort has been spent on understanding the role of dust in this process, the role of stellar pulsations and how they affect the dust formation has received less attention. In dynamic atmosphere and wind models the stellar pulsation is often simulated by prescribing a simple sinu- soidal variation in velocity and luminosity below the atmosphere. We experiment with different shapes of the luminosity variation and with phase shifts relative to the gas ve- locity to determine how this changes wind velocity, mass loss and the structure of the stellar atmosphere.

87 Atomic Hydrogen in the Circumstellar Envelope of the Carbon Star IRC+10216

L. D. Matthews, E. Gerard, T. Le Bertre S1-14

IRC+10216 (CW Leo) is the nearest and best-studied carbon star. It is undergoing mass − − loss at a high rate (∼ 10 5 M yr 1) and is believed to be nearing the end of its lifetime on the AGB. Mass loss from IRC+10216 has led to the formation of a structurally and chem- ically complex circumstellar envelope (CSE) that extends to more than half a parsec from the star. Although the CSE of IRC+10216 has been widely studied through emission from dust and molecular lines, the properties of the predominant CSE constituent – hy- drogen gas – have remained poorly known, including the total mass and extent of the circumstellar hydrogen and the ratio of atomic to molecular hydrogen throughout the en- velope. We will present new insights into these questions based on results from a study of IRC+10216 in the H i 21-cm line using the Very Large Array and the Robert C. Byrd Green Bank Telescope. We will also highlight the value of the H i line as a probe of the interface between the circumstellar and interstellar environment.

Imaging Radio Photospheres with the Jansky Very Large Array

L. D. Matthews, M. J. Reid, K. M. Menten S1-15

At centimeter wavelengths, long period variable stars have detectable ”radio photo- spheres” that lie at roughly twice the classic photospheric radius measured at optical wavelengths. The study of these radio photospheres provides a means to probe the at- mosphere of an AGB star just inside the region where dust formation occurs and the stellar wind is launched. We will present results from a new radio photosphere imaging program based on data from the Jansky Very Large Array (JVLA). The extraordinary sen- sitivity of the newly upgraded JVLA coupled with the high angular resolution of these data (∼ 40 mas) enables us to resolve the radio photospheres and to obtain precise measure- ments of their shapes and sizes. New results will be compared with previous studies to address the question of whether the flux density and/or shape of the radio photosphere changes significantly over the stellar pulsation cycle.

88 Dynamics of circumstellar envelopes of AGB stars

N. Netzer S1-16

The dynamics of dust-driven stellar outflows is discussed, on the basis of the solution of the radiative transfer equations coupled with the dynamical equation. The method is an expansion of the radiation intensity function in terms of orthogonal functions. This procedure was developed initially for AGB stars, albeit can be used also for other stars of spherical symmetry. Currently a numerical way is being developed for including the case of time dependent mass loss rate.

The deviations from central symmetry in the close environment of RS Cnc

P.T. Nhung, D.T. Hoai, P. Darriulat, T. Le Bertre, J. M. Winters S1-17

The close environment of RS Cnc presents a clear axi-symmetry which is described in the related contribution (Hoai et al., this conference). We obtained a satisfactory fit of very detailed CO data obtained at IRAM. However, there are still some differences that may have a systematic character. In this contribution, we investigate how to directly bring to evidence deviations from central symmetry in spectral maps. We discuss the possi- ble relation between these deviations and the development of the general axi-symmetric structure of RS Cnc’s environment.

Cool Giant Atlases in the CRIRES-POP Project

C. Nicholls, T. Lebzelter; and the CRIRES-POP Team S1-18

The CRIRES-POP project will provide a public database of high resolution, high signal- to-noise near infrared spectra of stars spanning the HR diagram. A relevant part of this library for the AGB community will be the high quality reference spectra of several cool evolved giants. These atlases will be valuable references for future research, and will in- clude comprehensive line identifications, abundance measurements, and isotope ratios, alongside stellar parameters derived through the inclusion of other data sources. The CRIRES observations have been completed and reduction of the spectra, including im- proved telluric subtraction and wavelength calibration, is ongoing. Analysis and release of the cool giant atlases is expected to be completed within the next two years.

89 The true (sur)face of the carbon rich Mira R Fornacis

C. Paladini, J.-B. Le Bouquin, K. Ohnaka, F. Baron, J. Kluska, M. Wittkowski, J. Hron, A. Jorissen, F. Soulez, W. Nowotny, K. Eriksson, C. Lykou, J.-P. Berger, A. Luntzer, N. Blind, S. H. S1-19

In this contribution, I will present for the first time the "true face" of a carbon rich Mira star. In December 2012, we successfully observed the surface of R Fornacis with VLTI/PIONIER. The observations were carried out in three spectral channels across the H-band. The images show strong departure from spherical symmetry in all the spectral channels, being more pronounced in the short wavelengths where CO and possibly C2H2 are the major contributors. This is in contrast with all the images so far obtained with op- tical interferometry for AGB stars that show a roundish onion-like shape. On the other hand all the aforementioned images are from oxygen-rich Miras. Are the asymmetries of R For connected with the chemistry, or are those intrinsic to this specific object? While the photometry and the ISO spectrum can be reasonably fit with dynamic model atmo- spheres, we are not able to reproduce the interferometric observations. Not even the first lobe of visibility where the star is supposed to appear in first approximation symmetric. I will discuss this result in connection with the fact that R For is the archetype of carbon stars with reported dust obscuration event. I will conclude reporting on our small cam- paign of VLTI/MIDI observations on AGB carbon stars that underwent dust obscuration events, and discussing what the next generation of VLTI imaging instruments will bring to the AGB field.

90 RU Vir - a test case for dynamic model atmospheres

G. Rau, J. Hron, C. Paladini, M. Mečina, K. Eriksson, W. Nowotny, B. Aringer, M. A. T. Groenewegen S1-20

We analyse the ISO-spectrum, photometry, and MIDI-visibilities of the C- Mira Ru Vir. Amorphus carbon (amC) and silicon carbide (SiC) are the dust species in carbon-rich AGB stars. While amC is featureless in the spectrum, SiC has an evident spectral feature around 11.3 µm. The study of SiC is relevant because by its ejection into the interstellar medium by the stellar wind, SiC can be trapped in presolar grains (Hedrosa et al. 2013). However a detailed theory about SiC formation is still missing (e.g. Yasuda & Kozasa 2012 and references therein). This study aims at constraining the dust condensation radius and temperature of SiC dust, and investigates the atmospheric structure and the envelope of RU Vir. As preparatory work, we determined the effective temperature, the luminosity and the pa- rameters of the dusty envelope, using the radiative transfer code ”More Of Dusty” (MOD, Groenewegen, 2012) and hydrostatic model atmospheres (Aringer et al., 2009). The interferometric MIDI data are not well reproduced, therefore a sub-set of the dynamic models of Mattsson et al. (2010) are used. COMA (Aringer et al., 2009) is used to add the SiC dust. In addition, new observations obtained in April 2014 (VLTI/MIDI) are in- cluded in the comparison between dynamic models and observations. The results will be presented in this talk. Also, this work is related to the preparation of science with MATISSE.

U Microscopii at Minimum: A New Member of the M10 Class

R. F. Wing S1-21

The southern Mira variable U Mic, previously classified as M5e-M7e (GCVS), was ob- served at a deep minimum on May 17, 2014. Narrow-band measurements of TiO and VO features indicate a spectral type of M10, a classification seldom attained even among the large-amplitude Miras. Spectral types later than M8 are best judged by the strength of the VO feature near 1.06 micron, which is seen against a clean continuum and con- tinues to grow to the reddest colors. The observed minimum of U Mic appears to have been unusually deep. A quick-look estimate from a Johnson V image gives V = 14.8, as compared to its published range of V = 7.0-14.4 (GCVS). The corresponding human-eye visual magnitude would be about mvis = 15.3. The observations were made at the 0.9-m telescope operated by the SMARTS consortium at CTIO, as part of a long-term program to obtain spectral classifications for (southern) Miras that are predicted (by the AAVSO) to be close to minimum light at the times of the writer’s observing runs. Several examples of extremely late-type Miras will be shown.

91 Probing NH3 Formation in Oxygen-rich Circumstellar Envelopes K.-T. Wong, K. M. Menten, T. Kaminski, F. Wyrowski S1-22

The Ammonia (NH3) chemistry in circumstellar envelopes of AGB stars and red su- pergiants is poorly understood. Thermodynamic equilibrium (TE) chemistry predicts an − abundance of . 10 8, orders of magnitudes lower than values reported from observa- − − tions (∼ 10 7 −10 6). To date, there is no consistent model explaining the origin of high NH3 abundances. To better understand the physical conditions necessary for the for- mation of NH3, we analysed the NH3 J=2-1 and J=3-2 rotational lines observed with the Herschel/HIFI and complemented by previously published results for the J=1-0 line. The strength of these lines clearly confirms the high abundances contradiction to the TE predictions. From 1D radiative transfer modelling, we infer a total NH3 abundance of − 2.4 × 10 5, along with the ortho-to-para ratio of roughly 3:1, significantly higher than the statistical equilibrium value of 1. We will discuss these preliminary results and present the possible origin of NH3 in oxygen-rich circumstellar envelopes.

Magnetic fields in evolved stars

L. Sabin, Q. Zhang, N. Patel, R. Vázquez, A. A. Zijlstra, B. A. Zauderer, M. E. Contr- eras, P. F. Guillén, G. Ramos-Larios S1-23

The role of magnetic fields in late type stars and their envelope, such as Asymptotic Gi- ant Branch stars and their descendants, is poorly known from an observational point of view. Magnetic fields are however believed to have a (strong) influence on the dynamics and even the chemistry of these stellar objects. We therefore present sub-millimeter ob- servations realised with the Sub-Millimeter Array (SMA) which unveil the dust continuum polarisation in the binary (M9-10 III Mira variable and a A0 main sequence companion) evolved star OH 231.8+4.2. Assuming the current grain alignment theory, we were also able to trace the geometry of the magnetic field.

92 Session 2: Living Together

A Spiral Goes Viral - Observations and modeling of the complex circumstellar envelope around R Scl

M. Brunner, M. Maercker, W. H. T. Vlemmings, et al. S2-01

The complex circumstellar envelope around the carbon-rich asymptotic giant branch (AGB) star R Sculptoris has been observed with ALMA, revealing a remarkable and up to now unique geometry by combining a thin, spherically symmetric detached shell enclos- ing a spiral structure. With the comparison of ALMA data of three different spectral bands - covering different excitation states of the CO molecule - the gas structure and mass-loss evolution of this object can be analysed. A morphological comparison between molecular line data (ALMA) and dust images (Herschel/PACS) gives hints to the spatial distribution of both constituents of the circumstellar envelope, as well as interaction processes be- tween the different media. Dust continuum radiative transfer modeling of the detached shell around R Scl allows to constrain the dust parameters and delivers spectral energy distributions comparable to observations.

93 Detailed modelling of the circumstellar envelope of the S-type AGB star W Aquilae

T. Danilovich, P. Bergman, K. Justtanont, R. Lombaert, M. Maercker, H. Olofsson, S. Ramstedt, P. Royer S2-02

We present new Herschel HIFI and PACS sub-millimetre and far-infrared line observa- tions of several molecular species towards the S-type AGB star W Aql. S-type AGB stars are thought to be in a transitional phase between M-stars and carbon stars. We detect 62 new circumstellar lines from CO, H2O, SiO, HCN, and, for the first time in an S-type AGB star, NH3. We use these observations, which probe a wide range of gas temperatures, to constrain the circumstellar properties, including the stellar mass-loss rate, the veloc- ity profile, and circumstellar molecular abundances. Our model includes fully integrated H2O line cooling as part of the solution of the energy balance. This analysis forms the most comprehensive molecular study of an S-type AGB star to date, using one of the most detailed radiative transfer codes available. The radiative transfer calculations result − − in an estimated mass-loss rate for W Aql of 3.8 × 10 6 M yr 1 based on the 12CO lines. We also perform radiative transfer calculations for the other molecules. Notably, the NH3 abundance is high and in a relatively small envelope close to the star. We find it difficult to consistently model the HCN and CN data assuming that the latter is a photodissociation product of the former.

94 The Formation and Evolution of Eccentric Binary Systems

P. J. Davis, L. Siess, A. Jorissen S2-03

Observations are revealing a host of post-mass transfer binary systems in significantly eccentric orbits, such as Barium stars [1] and subdwarf-B + main sequence systems [2]. Their formation presents a challenge to modellers, as it is believed that tidal forces efficiently circularise the orbit. Using our state-of-the-art binary stellar evolution code BINSTAR [3], we explore the formation and evolution of eccentric binary systems within the framework of the osculating orbital theory. This scheme describes in a physically realistic manner the perturbing forces acting on the orbit arising from mass transfer [4]. Results are presented, showing the impact of wind losses on the orbital separation and eccentricity for a range of initial stellar and binary parameters. As an interesting case- study, we describe the formation channel of the eccentric white dwarf + main sequence binary IP Eri [5], which invokes a tidally-enhanced wind loss mechanism [6]. This scenario reproduces the observed properties of IP Eri remarkably well, and therefore presents a promising mechanism for the formation of related eccentric binary systems. References: [1] Jorissen A., 1999, IAU Symposium, 191, 437; [2] Vos et al., 2013, A&A, 559, 54; [3] Siess L., Izzard R., Davis P. J., Deschamps R., 2012, A&A, 550, 100; [4] Hadjidemetriou J., 1969, Ap&SS, 3, 330; [5] Merle et al., 2014, A&A (submitted); [6] Siess L., Davis P. J., Jorissen A., 2014, A&A (in press)

WISE View of RV Tauri Stars

I. Gezer, H. Van Winckel, Z. Bozkurt S2-04

RV Tauri stars are luminous population II Cepheids which show a characteristic light curve of alternating deep and shallow minima. Many of them are thought to be post-AGB stars. There are 170 RV Tauri variables in our galaxy and they are also found in the LMC and in the SMC. RV Tauri stars are chemically very diverse with only a few showing s-process abundances. The evolutionary nature of RV Tauri stars is not understood yet. Several RV Tauri stars were detected by IRAS to show an IR excess. They occupy a specific region in the IRAS color-color diagram and we know now that this location is indicative for the presence of a dusty disc. We have expanded the IRAS color-color diagram of RV Tauri stars with a similar one using WISE (Wide-field Infrared Survey Explorer). WISE was launched in December 2009 and scanned all sky in 3.4, 4.6, 12 and 22 µm wavelength range bands. Our aim is to systematically study the infrared properties of all 170 Galactic RV Tauri pulsators and differentiate between likely disc sources, expanding shells and objects without dust excess. The aim is to correlate infrared properties with chemical peculiarities and eventual binary nature of the central stars. This will lead to a better understanding of the evolutionary status of RV Tauri stars.

95 Recent results from the HERMES/Mercator radial-velocity monitoring of late- type stars

A. Jorissen, H. Van Winckel, S. Van Eck S2-05

The HERMES spectrograph has been operating since 2009 on the 1.2 m Mercator tele- scope at La Palma. The radial velocities of a pooled list of targets are being monitored for about 130 nights/yr. We present highlights of this monitoring campaign for barium and S stars (mass-function distribution), CEMP binaries, long-period binary CSPN, and a seemingly spectroscopic binary about an AGB star.

Binary stars in the Fourier space

C. Paladini, A. Jorissen, C. Siopis, G. Sadowski, D. Shulyak, G. Li Causi S2-06

Observing late type stars with an interferometer is rather "easy" because of their bright- ness in the near-infrared and their extended atmosphere. On the other hand the inter- pretation of interferometric observations can be very tricky, especially when it comes to asymmetric structures detected via phase measurements. Our team developed dedi- cated 2D models to interpret observations of binaries. The models are generated through a software that simulates binary systems in a realistic way, using a Roche representation of the stellar surfaces and the MARCS stellar atmosphere models. In this contribution we describe the results obtained by simulating interferometric data.

Hydrodynamics of mass transfer in binary star systems

S. Toupin, L. Siess, K. Braun, A. Jorissen S2-07

No formulation is currently available to correctly treat the exchange of mass and angular momentum due to wind between the components of a long-period binary system such as the progenitors of barium stars. The goal of this research project is to derive prescrip- tions for the rates of mass and angular-momentum transfer in long-period binary systems, based on 3D SPH simulations. In this poster, we present the first steps towards a consis- tent modeling of such mass transfers. A special attention is paid to the physics of mass loss by the giant star. One of the big achievements of our developments is the ability to fully reproduce for the first time in 3D the standard wind model developed by Bowen.

96 Unwinding the secrets of thermal pulses and sculpted winds: ALMA observa- tions of R Sculptoris

W. Vlemmings, M. Maercker, S. Mohamed, S. Ramstedt, et al. S2-08

Our recent ALMA observations of the CO emission around the carbon AGB star R Sculp- toris show its detached shell and circumstellar medium around this star in unprecedented detail. They confirm that the detached shell is formed due to the change in mass-loss rate and expansion velocity during a thermal pulse. The data also reveal a clear, and previ- ously unobserved, spiral structure within and connected to the detached shell, indicating the presence of a companion star. The observations highlight one of the observable con- sequences of hitherto hidden binary companion in the circumstellar envelope of an AGB star. We also find an additional possible consequence of binarity (or possibly an active stellar chromosphere), namely the surprising variability of observed 13CO/12CO isotope ratio throughout the stellar wind. This result presents a possible further probe for binary action that ALMA will be able to explore in depth.

97 Session 3: What is left

FRUITY upgrades on AGB evolution and nucleosynthesis

S. Cristallo, O. Straniero, L. Piersanti S3-01

AGB stars are among the major polluters of the interstellar medium. These objects pro- duce both light (C,N,O,F,Na) and heavy elements (via the slow neutron capture process, the s-process). Our AGB models are available on the on-line FRUITY database, in which we provide surface isotopic compositions and yields from hydrogen to lead. Currently, FRUITY is hosting chemical features of low-mass AGB stars only (1.3 ≤ M/M ≤ 3.0). Here, we present a new set of intermediate mass AGB models (4.0, 5.0 and 6.0 M with -2.15 ≤ [Fe/H] ≤ +0.15). We discuss their physical and chemical properties, highlighting the differences with respect to the on-line low mass range set. Moreover, we check the reliability of our models by comparing them to observed quantities, such as the initial-to- final mass relation and the AGB Luminosity Functions.

The Continuing Evolution of Sakurai’s Object

K. Hinkle, R, Joyce S3-02

Sakurai’s Object (V4334 Sgr) transitioned from a hot white dwarf to an AGB star in the 1990s. The transition to the AGB was attributed to a post-AGB final flash. V4334 Sgr underwent rapid cooling and dust obscuration becoming as faint as K ∼ 25 by 2007. This stage of evolution has ceased. Near-IR observations starting in 2010 show that V4334 Sgr has brightened to K = 14.2 and the effective temperature has increased to ∼ 590 K. AO images show a central source and two extended globules defining a position angle similar to that of the PNe. The globules now span a spatial extent of ∼ 0.3 arcsecond consistent with sizes derived from spectral energy distributions and a − debris cloud expanding at 0.055 mas d 1 since 1998. Near-IR 0.85 – 2.5 µm spectra reveal helium lines attributed to a wind-interaction shock. The He I 1.0830 µm emission − has a spectral width of ∼ 1000 km s 1 and a spatial extent of ∼ 1.4 arcsecond. The he- lium shell is fragmented, spatially asymmetric, and five times larger than the the dust debris cloud. The status of V4334 Sgr as a final flash object will be discussed.

98 Fluorine abundances of AGB stars in stellar clusters

A. Hren, T. Lebzelter, B. Aringer; K. H. Hinkle, W. Nowotny S3-03

For the synthesis of fluorine a number of possible formation sites were proposed: thermal pulsing AGB-stars, Type II supernovae and Wolf-Rayet stars. This study is meant to observe the abundance of fluorine, [F/H] in a number of AGB-stars in stellar clusters and compare it with the stars’ measured C/O-ratio, which serves as an indicator of the on-going third dredge-up. Studying several stars in a cluster allows to investigate the change of the fluorine abundance along the evolution on the giant branch. High resolution infrared spectra in the K- and H-bands were obtained using the PHOENIX spectrograph mounted on the Gemini South telescope, aiming at the HF-features R7, R15 and R16 for the estimation of the fluorine abundance. The target-list includes primarily O-stars in the three globular clusters NGC 1806, NGC 1846 and NGC 1978 in the LMC as well as Rup 106 and 47 Tuc in our galaxy. For the modelling of the synthetic spectra, the COMA-code was used. We find consistent [F/H] values at similar C/O for all our target stars.

Understanding AGB nucleosynthesis from chemical composition studies of CH stars

D. Karinkuzhi, A. Goswami, N. S. Shantikumar S3-04

CH stars are known to show enhanced abundances of carbon and heavy elements (neutron-capture elements). They are metal-deficient population II objects. Luminosi- ties of these stars indicate that they are mostly giants; hence, the observed enhanced abundances of heavy elements are unlikely to have been produced inside the stars during stellar nucleosynthesis. As most of the CH stars are known to be binaries, the observed abundance anomalies are generally explained on the basis of a binary picture involving a low mass companion evolving through AGB phase. Detailed chemical analysis of CH stars can thus provide the knowledge about the nucleosynthesis taking place in the com- panion AGB stars. We have conducted a detailed chemical composition study for a large sample of CH stars. Results obtained from this study will be presented.

99 Spectroscopy of the extremely metal-poor red giant HE0056-3022

A. Klavins, A. Barzdis, O. Smirnova S3-05

Among the oldest objects in the Universe metal-poor stars can be used to test stellar evolution in the early Universe. Detailed analysis of such stars can provide important data for stellar astrophysics and cosmology as well. This research is based on high- resolution spectroscopy of the poorly studied extremely metal-poor star HE0056-3022. The results about its chemical composition and atmospheric parameters are collected and analyzed, and possible evolutionary status of the star and the source of its chemical peculiarities are reviewed. Our derived abundance of iron [Fe/H] = −3.25 dex proves that HE0056-3022 is extremely metal-poor. From the analysis of the obtained abundances for other elements we conclude that the star most likely is on the Red Giant Branch and experiencing Helium core burning flash. The atmosphere of the star is abundant in alpha elements, especially oxygen with [O/Fe] = +1.45. These elements mainly forms in Type II Supernova explosions. The possible binary origin of the star is also discussed.

Are PPN jets initiated after evolution to the PPN phase?

B. M. Lewis S3-06

AGB stars with progenitor masses . 8 M evolve through a pulsating, red giant phase as they slowly lose mass in a spherically-symmetric, slowly-expanding wind prior to their evolution to proto planetary nebulae (PPN). Most optically resolved PPN on the other hand exhibit a much more complex shell morphology by virtue of the interaction of their bipolar jets with the circumstellar shell generated during the AGB phase. So when are the jets initiated? In the case of the low progenitor mass PPN IRAS18455+0448 the an- swer to this question may be adduced from temporal changes in its complement of OH masers. While O-rich AGB stars usually exhibit a characteristic, double-peaked spec- trum of 1612 MHz OH masers, the signature of the low velocity outflowing wind, an early signal for their transition to the PPN phase is the cessation of both pulsation and mass loss. IRAS 18455+0448 recently made that transition. Its ∼ 2 Jy 1612 MHz masers when discovered in 1988 had almost disappeared by 1998. Their final exponential decline was monitored at Arecibo (ApJ 548, L77: 2001). On the other hand its mainline masers con- tinued to exhibit a gradual decline in intensity until 2010, when they abruptly changed with the eruption of strong new features well beyond its velocity range as an OH/IR star. These features are consistent with the interaction of a newly initiated jet with the circumstellar shell. That suggests that jets from stars with low progenitor masses are usually initiated after transition to the PPN phase. Indeed IRAS18455+0448 may be the prototype for an ’OH-fountain’ class of objects analogous to the set of ’water fountain’ sources.

100 Li-rich AGB/RGB stars: abundance correlations with stellar properties

W. J. Maciel, R. D. D. Costa S3-07

Evolved metal-rich stars, such as AGB/RGB stars usually display strong Li underabun- dances, which is explained by the fact that this element is easily destroyed in the high temperatures of the stellar interiors. However, many AGB/RGB stars display higher Li abundances, namely, log (Li/H) + 12 > 1.5, which is presently attributed to the Cameron- Fowler mechanism and to hot bottom burning in these stars. The primordial Li abun- dances are generally associated with the Spite plateau as observed in metal poor stars. More recently, is has been shown that there is in fact some correlation between the Li abundance and the stellar metallicity, so that the plateau is not exactly flat. In a previous work, we have shown that the correlation observed in metal-poor dwarf stars is valid, in average, for Li-rich AGB/RGB stars. However, when the stars are individually considered, this correlation is weakly defined, which suggests that other stellar properties apart from the metallicity also play an important role in the Li production mechanism. In this work, we consider a large sample of Li-rich AGB/RGB stars and search for correlations involv- ing the Li abundances and some stellar parameters, such as the effective temperature, luminosity, radius, gravity, mass loss rates and s-element abundances, apart from the metallicity. We find that some of these correlations are statistically meaningful, particu- larly those involving the stellar luminosity and radius, which may throw some light on the Li production processes in AGB/RGB stars.

Li nucleosynthesis in AGB stars and a new estimate for the 7Be half-life

S. Palmerini S3-08

AGB stars with M < 2 M contribute to the Li abundance in galaxies by the coupled effects of nucleosynthesis and non convective mixing mechanisms. However, observed Li abun- dances are difficult to explain, as they cover a wide spread. Various uncertainties affect model attempts and a large one concerns the nuclear process for the 7Li production. In- deed, the rate of e-captures on 7Be was properly estimated only for the solar core, whose temperature and density are rather differ from those of AGB regions where Li might be synthesized. Hence extrapolations are unreliable. Here, we discuss the consequences on Li nucleosynthesis in AGB stars of an ad-hoc estimate of the 7Be half-life. Nucleosyn- thesis calculations performed by using the new rate for e-capture better reproduce the trend of Li observed in most AGB stars. However, Li abundances higher than A(Li)=1.5 are not explained, contrary to what was found before. Due to this fact the enrichment in Li of the envelopes of low mass AGB remains a challenge for stellar nucleosynthesis, which might be solved by peculiar mixing episodes induced by the stellar magnetic field.

101 The Evolution of ONeMg Cores with MESA

J. Schwab, E. Quataert, L. Bildsten S3-09

We present calculations of the evolution of degenerate cores composed primarily of oxygen, neon, and magnesium which are undergoing compression. We make use of the state-of-the-art MESA stellar evolution code, with updated weak reaction rates from Martinez-Pinedo et al. (2014). We discuss differences between cores formed during the late stages of evolution of super asymptotic giant branch stars and those formed as the remnant of a merger of two white dwarfs. We illustrate the sensitivity of our results on ul- timate fate of these cores (be it explosion or collapse) to uncertainties in the microphysics as well as choices related to our 1D numerical treatment.

Chemical Abundances in Post-AGB Stars

G. Şehitoğlu, Z. Bozkurt S3-10

The post-AGB type objects that have the chemical abundance study in the literature have been complied. Based on the chemical abundance data of selected post-AGB stars, traces on the nucleosynthesis processes together with mixing processes occurred in the previous evolutionary stage have been searched. 174 objects which have chemical abun- dance study have been found and spectral type and temperature distribution of these ob- jects have been investigated to see the characteristics of Post-AGB objects. Metallicity, [Fe/H], carbon-oxygen ratio, [C/O], α-elements, [α/Fe], s-process elements, [s/Fe], and refractory elements distributions have also been studied.

The s-Process Enrichment of the Globular Clusters M4 and M22

L. Shingles, A. I. Karakas, R. Hirschi, C. K. Fishlock, D. Yong, G. S. Da Costa, A. F. Marino S3-11

I will discuss the s-process enrichment of two galactic globular clusters, M4 and M22. M4 has constant abundances of Fe and neutron-capture elements, but the entire cluster is more enriched with s-process elements (Rb, Sr, Y, Ba, Pb) than other clusters of a similar metallicity. In M22, two stellar groups have been identified with different abundances of Fe and s-process elements. We construct chemical evolution models in which s-process elements are produced by 1) massive stars with rotation, or 2) a generation of AGB stars that span a range of stellar masses. I will discuss the implications of our results on the likely polluter stars and timescales for the s-process enrichment in M4 and M22.

102 The 89.087 GHz HCN maser in IRAS 15082-4808

C. L. Smith, A. A. Zijlstra, G. A. Fuller S3-12

Masers are a unique instrument in the investigation of the structure, dynamics and com- position of astronomical environments. In the circumstellar envelopes of carbon-rich AGB stars, the only molecule commonly observed as a maser is HCN. We have identified a new 89.087 GHz vibrational HCN maser in IRAS 15082-4808 (V358 Lup), bringing the total number of stars known to host this maser to ten. Three epochs of observations have been obtained, with different line intensities and profile shapes observed. The ve- locity of the major maser component is offset with respect to the systemic velocity of the envelope by -2.0+/-0.9 km/s, consistent with the offset velocities of the masers in the remaining nine stars. Maser intensity with pulsation phase has been investigated in all ten stars. Comparing the observed characteristics of this maser with AGB model atmo- spheres constrains the originating region to between 2 and 4 stellar radii, between the pulsation shocks and the onset of dust acceleration.

ALMA observations of the coldest place in the Universe: The Boomerang Nebula

W. Vlemmings, R. Sahai, L. A. Nyman, P. Huggins S3-13

Our recent ALMA observations of the CO emission around the carbon AGB star R Sculp- toris show its detached shell and circumstellar medium around this star in unprecedented detail. They confirm that the detached shell is formed due to the change in mass-loss rate and expansion velocity during a thermal pulse. The data also reveal a clear, and previ- ously unobserved, spiral structure within and connected to the detached shell, indicating the presence of a companion star. The observations highlight one of the observable con- sequences of hitherto hidden binary companion in the circumstellar envelope of an AGB star. We also find an additional possible consequence of binarity (or possibly an active stellar chromosphere), namely the surprising variability of observed 13CO/12CO isotope ratio throughout the stellar wind. This result presents a possible further probe for binary action that ALMA will be able to explore in depth.

103 Session 4: Old & new dust

Mass loss on the RGB

M.A.T. Groenewegen S4-01

Our efforts are described to detect mass-loss on the RGB through analysis of the SEDs, and molecular line emission of nearby RGB stars.

PAH Formation in O-rich Planetary Nebulae

L. Guzman-Ramirez, E. Lagadec, D. Jones, A. A. Zijlstra, K. Gesicki S4-02

Polycyclic aromatic hydrocarbons (PAHs) have been observed in O-rich planetary neb- ulae. This combination of oxygen-rich and carbon-rich material, known as dual-dust or mixed chemistry, is not expected to be seen around this objects. We recently pro- posed that PAHs could be formed from the photodissociation of CO in dense tori. Using VISIR/VLT, we spatially resolved the emission of the PAH bands and ionised emission from the [SIV] line, confirming the presence of dense central tori in all the observed O- rich objects. Furthermore, we show that for most of the objects, PAHs are located at the outer edge of these dense/compact tori, while the ionised material is mostly present in the inner parts of these tori, consistent with our hypothesis for the formation of PAHs in these systems. The presence of a dense torus has been strongly associated with the action of a central binary star and, as such, the rich chemistry seen in these regions may also be related to the formation of exoplanets in post-common-envelope binary systems.

104 Runaway growth of fractal dust grains

L. Mattsson, J. D. Munkhammar S4-03

We have generalised the commonly used moment method for modelling dust condensa- tion (grain growth) to include the case of grains with fractal structure. Fractal grains have large surface area, which leads to more efficient condensation, but the growth rate is usu- ally not without bounds. However, there is a special limit case, where the volume-area ratio is constant (corresponding to, e.g., a very rough grain surface or non-compacts ag- gregates), which is particularly interesting (as well as convenient) from a mathematical point of view. We present here ’proof of concept’ for runaway growth of fractal grains, which may explain very fast grain growth suggested by some observations. If dust grains from AGB stars have ’rough surfaces’, it may have important implications for our under- standing of dust and wind formation in AGB stars.

Round, Thin & Dusty - Detached Shells as Tracers of Highly Variable Stellar Mass-Loss

M. Mečina, F. Kerschbaum, M. Groenewegen, R. Ottensamer, A. Mayer, A. Luntzer, L. Decin, J. Blommaert, B. Vandenbussche, Th. Posch, C. Waelkens S4-04

For the Mass-loss of Evolved StarS (MESS) program, the high spatial resolution of the PACS photometer on board the Herschel space observatory was employed to map the dusty environments of Asymptotic Giant Branch (AGB) and Red Supergiant (RSG) stars. Among the morphologically heterogeneous sample, a small fraction of targets is enclosed by spherically symmetric detached envelopes. Based on observations in the 70 µm and 160 µm wavelength bands, we investigate the surroundings of several carbon semiregu- lar variables, which show evidence for a history of highly variable mass-loss. We observe dust counterparts of known CO shells as well as detect previously unknown extended structures around some stars, even multiple shells. MoD, a modification of the DUSTY radiative transfer code, is used to model the dust component of the detached shells and derive the dust mass and temperature and estimate the corresponding mass-loss rates (MLR) and involved timescales. We present our modelling approach and show its appli- cation to several sources, which enables us to set further constraints on the formation scenario. In addition, the encountered uncertainties, e.g. the optical dust properties, were investigated and are discussed along with other remaining obstacles.

105 Modelling the AGB dust evolution

W. Nowotny, H.-P. Gail, Th. Posch, B. Aringer S4-05

We present on this poster results of our efforts to model the circumstellar dust shells of evolved red giants. The modelling approach is based on an improved version of the code to calculate stationary wind models as described in Ferrarotti & Gail (2006). With the focus on a detailed dust mineralogy we will illustrate the outcome concerning dust grain formation (different species, condensation degrees, grain sizes, etc.) as well as the resulting spectral energy distributions from the visual to the far-IR.

How to build pentagons and heptagons from hexagons around AGB stars

S. Öttl, S. E. Huber, F. Niederwanger, S. Kimeswenger S4-06

Polycyclic aromatic hydrocarbons (PAHs) are known to be one of the carriers of the ubiq- uitous aromatic infrared bands that are frequently observed in post-AGB stars and plan- etary nebulae (PNe) (Matsuura et al. 2014). Although PAH features are identified in a wide variety of environments, the characteristics of the individual molecules is not clear so far. Several emission features are observed, but cannot be explained. Therefore a sophisticated understanding of all possible types and subtypes is required. This study presents a theoretical investigation of the IR spectra of PAHs containing (5, 7)-member ring defects. Such defects consist of pentagons and heptagons instead of some of the hexagons usually constituting PAHs. Using density functional theory, the influence of those defects on the IR spectra of pyrene (C16H10) and coronene (C24H12) and their cations and anions were examined in detail. Additionally, the potential energy surface of the neutral species was explored. The environment of carbon rich AGB stars seems to be a very suitable location for PAH formation (Allamandola et al. 1989). In terms of the de- fect, the formation of 5-member rings within the growth of carbon molecules is discussed in Whitesides & Frenklach (2010). In this study, an alternative formation pathway is taken into account. Especially the environments of AGB stars or PNe seem to be well suited to enable this alternative formation pathway. The environment strongly enables the transi- tion from the ground state to the defect state. Therefore the knowledge of the IR spectra of these molecules will support the investigations in understanding the unidentified IR emission bands.

106 New Faint Ring-Like Structures Found in PNe, PPNe and AGB stars

G. Ramos-Larios, M.A. Guerrero, L. Sabin, E. Santamaria, A. Marquez-Lugo S4-07

Many objects like PNe, PPNe and Carbon stars show rings and shells related to the remnants of the circumstellar envelopes of the asymptotic giant branch phase (AGB). After an extensive search in the HST and Spitzer archives we found ring-like structures in several objects. Following the image analysis described by Corradi et al. (2004), and unsharp masking techniques it was possible to effectively remove the underlying halo emission, enhancing the ring structures. We mention in the results some hypotheses about the origins of these rings.

An Exploration of the Dust Spectral Features of the Carbon-Rich Star V Cyg Through Time and Space

M. Reel, A. Speck, G. C. Sloan, K. Volk S4-08

Carbon-rich AGB stars are surrounded by circumstellar shells of gas and dust. The dust is dominated by carbon (probably graphitic) and silicon carbide (SiC), which is the source of the observed 11 µm spectral feature. We investigate the nearby carbon star V Cyg which has been observed numerous times over the past few decades. By analyzing the temporal spectral variations associated with the stellar pulsation cycle we study how the pulsation cycle affects the circumstellar dust. The Infrared spectrum of the star also shows many prominent molecular absorption bands, as well as the "30 µm" emission feature which has previously been attributed to magnesium sulfide (MgS). In addition to the temporal data, we have also obtained spatially-resolved spectroscopic data for the dust shell(s) around V Cyg. Combining these various spectral observations with AAVSO data on variations in the visual magnitude we investigate temporal variations in both the 11 µm and 30 µm spectral features and sought to correlate these temporal variations with the spatial variations in the 11 µm feature. Our results indicate many spatial correlations within the 11 µm feature parameters, as well as correlations which may suggest a carrier of the 30 µm feature other than pure MgS.

107 A testing of the dust shell model for Long Secondary Period of AGB stars

M. Takayama, P.R. Wood, Y. Ita S4-09

The origin of the variability of some red giant stars which show Long Secondary Period (LSP) is one of the outstanding problems. This period is roughly 400-1500 d and it is about 4 times longer than the fundamental mode of Mira variables. Now long term J, H, and K light curves have become available for large numbers of the luminous red giant stars in the SMC. By using those new dates, along with OGLE V and I light curves, in oxygen rich stars we found that J-K colour gets bluer when a star dims. We interpreted those changes as being due to increasing water absorption by the development of a layer of dense cool gas above the photosphere. This suggests that the LSP phenomenon is associated with the ejection of matter from the stellar photosphere. To explain the broadband light variations from the optical to the NIR regions, we tested the dust shell models for the variability of a sample of luminous LSP stars.

Dust production by AGB stars in the Solar Neighborhood

A. Trejo, C. Kemper, S. Srinivasan S4-10

AGB stars are the biggest contributor of the total dust mass injected into the ISM of galaxies. Although the dust production rate by AGB stars can be effectively estimated for other Local Group galaxies, it remains notoriously hard to derive for the Milky Way, due to extinction and the large uncertainties of the distance determinations for dusty AGB stars. In this work, we will take steps towards the determination of the total dust mass loss rate from AGB stars in the Milky Way. The last estimate of this dust injection rate was done in the late ’80s. Using new infrared facilities (WISE, 2MASS, and others), it is possible to provide a better estimate. This work is a contribution to that effort, and it aims to provide new insight of the discrepancy of the dust mass produced by AGB stars and that estimated to be present in the ISM. For this, we first calculate the injection rate in the Solar Neighborhood, using a volume-limited sample. We make use of the GRAMS model grid to estimate the dust production for this sample of AGB stars. However, such a study is very challenging, as the most enshrouded, and therefore dustiest objects do not appear in the Hipparcos catalogue, making their distances, and therefore their luminosities and dust production rates, rather uncertain. In addition, we will compare the derived dust production rates with those of the Magellanic Clouds and other Local Group galaxies, for which the distance determination problems do not exist.

108 Low-temperature and high-temperature IR spectra of spinel and corundum and their application to the spectra of AGB stars

S. Zeidler, H. Mutschke, Th. Posch S4-11

In the IR spectra of many oxygen-rich AGB stars, emission bands at 13 micron and 32 micron are detected. These infrared bands probably originate from ionic vibrations in refractory aluminum oxides: either in corundum or in spinel. Both corundum and spinel have been discovered in meteorites as presolar grains from AGB stars. Since they are among the first minerals that condense in the outflows of evolved stars, these oxides may serve as seeds for the formation of other, more abundant stardust minerals such as forsterite and enstatite. Until very recently, the infrared spectra of minerals that were used for the comparison with astronomical data were based on room-temperature mea- surements. However, none of the laboratory spectra matched the astronomical features at for the 13 and 32 micron completely. Given that the temperature of a stardust species directly influences its IR active modes, the position and shape of small particle spectra will also change as a function of temperature. Thus, comparing astronomical spectra with only room temperature spectra is not sufficient. We have measured the mid-infrared reflectance spectra of synthetic spinel and corundum in a temperature range of 10 K to 928 K. Subsequently, we fitted the data with a four-parameter semi-quantum model in or- der to derive the refraction (n) and the absorption (k) indices of these materials. From both n and k, we have calculated small particle spectra of spinel and corundum for different grain shapes. We then compared these spectra with dust emission spectra of selected AGB stars, focussing on the above mentioned features at 13 and 32 micron. Thereby, we were able to set stronger constraints on the possible temperatures and grain shapes of corundum and spinel grains in circumstellar shells.

109 Temperature-dependent optical constants of olivine and enstatite

S. Zeidler, H. Mutschke, Th. Posch S4-12

The existence of crystalline silicates (especially of the olivine and pyroxene type) in var- ious dusty circumstellar environments is a well-known fact supported by infrared spec- troscopic observations (ISO, Spitzer) revealing vibrational resonance features typical for these minerals. While in single AGB stars the mass ratio of crystalline vs. amorphous silicates is usually relatively low, a high crystallinity of silicate dust is found in post-AGB disk sources (e.g. Gielen et al. 2008, 2011). Amorphous silicates are likely processed in these disks at the high temperatures prevailing in the vicinity of the stars. The analysis of the spectra of such objects relies on optical constants n (refraction index) and k (ab- sorption index) of reference minerals measured in the lab, which inherit the positions and widths of the resonance features. An important issue in this respect is the temperature de- pendence of the vibrational resonances of crystals regarding their resonance frequency and damping parameter (Maradudin and Fein, 1962; Cowley, 1963). Data at low and particularly at elevated temperatures, however, are still rare, which is problematic for de- tailed analyses aiming for instance on the precise composition (e.g., the iron content) or the particle size of crystalline silicate dust, which indicate the state of dust processing. In our poster we present the results of spectroscopic reflection measurements on samples of natural (terrestrial) olivine and enstatite (Mg-rich orthopyroxene) with iron contents of 11 and 8%, respectively. We have measured the reflectivity in the wavelength range of 5 to 80 micrometers for different crystal orientations for temperatures between 10 and 928K with the aid of a liquid-helium cryostat and a high-temperature, high-pressure cell, respectively. We fitted the data with a Lorentzian oscillator model in order to obtain the optical constants and simulated emission spectra of particles of olivine and enstatite ap- plying the "Distribution of Form Factors" model. We demonstrate the way of applying our new data to the interpretation of observed spectra by comparing with the ISO spectrum of IRAS 09425-6040 (Molster et al. 2001). References: Cowley R.A., 1963, Advances in Physics, vol. 12, no. 48, 421 Gielen, C. et al., 2008, A&A, 490, 725 Gielen, C. et al., 2011, A&A, 533, A99 Maradudin A.A. & Fein A.E., 1962, Phys. Rev. B, 128, 6 Molster, F.J. et al., 2001, A&A, 366, 923

110 Session 5: Resolved and unresolved Populations

Is There a Metallicity Ceiling to Form Carbon Stars? - A Novel Technique Reveals a Scarcity of C-stars in the Inner M31 Disk

M. L. Boyer, L. Girardi, P. Marigo, B. F. Williams, B. Aringer, W. Nowotny, P. Rosen- field, C. E. Dorman, P. Guhathakurta, J. J. Dalcanton, J. L. Melbourne, K. A. G. Olsen, D. R. Weisz S5-01

We use medium-band near-infrared (NIR) Hubble Space Telescope WFC3 photometry with model NIR spectra of Asymptotic Giant Branch (AGB) stars to develop a new tool for efficiently distinguishing carbon-rich (C-type) AGB stars from oxygen-rich (M-type) AGB stars in galaxies at the edge of and outside the Local Group. We present the results of a test of this method on a region of the inner disk of M31 and find a surprising lack of C stars, contrary to the findings of previous C star searches in this and other regions of M31. We detect only 1 candidate C star (plus up to 6 additional, less certain C stars candidates), − resulting in an extremely low ratio of C to M stars (C/M = 3.3(+20)(-0.1)×10 4) that is 1-2 orders of magnitude lower than other C/M estimates in M31. The low C/M ratio is likely due to the high metallicity in this region which impedes stars from achieving C/O > 1 in their atmospheres. Previous C star identifications in this region using JHK colors are likely misidentified M stars with deep water absorption near 1.4 microns. These observations provide stringent constraints to evolutionary models of metal-rich AGB stars and point to a metallicity threshold above which M stars are unable to make the transition to C stars, dramatically affecting AGB mass loss and dust production and, consequently, the observed global properties of metal-rich galaxies.

111 The stellar properties of asymptotic giant branch stars in the dwarf irregular galaxy IC 1613

S.-H. Chun, M. Y. Jung, M. Kang, DS. Jung, Y.-J. Sohn S5-02

Broadband near-infrared images obtained with the WIRCam array of Canada-France- Hawaii Telescope are used to investigate the properties of resolved asymptotic giant branch (AGB) stars in the dwarf irregular galaxy IC 1613. AGB stars were selected in the color-magnitude diagram of various color indices with a wide wavelength baseline, obtained by combining our data with existing optical imaging data. We examined the distribution of AGB stars on the (J-K, H-K) color-color diagram, and discriminated 140 carbon-rich and 306 oxygen-rich M-giant AGB stars. We investigated the mean magni- tudes, colors and bolometric luminosity functions of C stars and M-giants stars. A com- parison of the theoretical isochrone with the color distribution of M-giant stars indicates that most of the bright M-giant stars in IC 1613 were formed at 1 Gyr. The number ratio of C-stars and M-giants, the C/M ratio, was estimated, and the metallicity in IC 1613 was derived using the C/M ratio. We also examined the local C/M ratio according to the posi- tion of the H II region and H I gas of IC 1613, and found that C/M ratios for the H II region and H I gas seem to be somewhat lower than that for the cavity of H I gas.

112 Enhanced Nitrogen in morphologically disturbed blue compact galaxies at 0.20 < z < 0.35: Probing galaxy merging features J. Chung, S.-C. Rey, E.-C. Sung, B.-S. Yeom, A. Humphrey, W. Yi, J. Kyeong S5-03

We present a study of correlations between the elemental abundances and galaxy mor- phologies of 91 blue compact galaxies (BCGs) at z = 0.20−0.35 with Sloan Digital Sky Survey (SDSS) DR7 data. We classify the morphologies of the galaxies as either "dis- turbed" or "undisturbed" by visual inspection of the SDSS images, and using the Gini coefficient and M20. We derive oxygen and nitrogen abundances using the Te method. We find that a substantial fraction of BCGs with disturbed morphologies, indicative of merger remnants, show relatively high N/O and low O/H abundance ratios. The major- ity of the disturbed BCGs exhibit higher N/O values at a given O/H value compared to the morphologically undisturbed galaxies, implying more efficient nitrogen enrichment in disturbed BCGs. We detect Wolf-Rayet (WR) features in only a handful of the disturbed BCGs, which appears to contradict the idea that WR stars are responsible for high nitro- gen abundance. Combining these results with Galaxy Evolution Explorer GR6 ultraviolet (UV) data, we find that the majority of the disturbed BCGs show systematically lower values of the Hα to near-UV star formation rate ratio. The equivalent width of the Hβ emission line is also systematically lower in the disturbed BCGs. Based on these re- sults, we infer that disturbed BCGs have undergone star formation over relatively longer timescales, resulting in a more continuous enrichment of nitrogen. We suggest that this correlation between morphology and chemical abundances in BCGs is due to a difference in their recent star formation histories.

113 A WFCAM near-infrared survey of AGB stars in M31 dwarf satellites

D. Crnojevic, A. Ferguson, M. Irwin S5-04

I present results from a UKIRT/WFCAM wide-field near-infrared survey of dwarf galaxies around M31. In particular, I focus on the dwarf elliptical satellites (NGC147, NGC185, NGC205 and the compact elliptical M32). This is the first time these objects are imaged with such a wide field of view (∼ 1 deg2), thus permitting not only to derive their phys- ical properties (in particular, ages and metallicities from the colors and luminosities of C- and O-rich luminous AGB stars) but also to trace possible radial gradients and global structures over the whole extent of the dwarfs. The results will be discussed in the con- text of the targets’ interaction with M31/with each other, and their possible morphological transformation. At the same time, by targeting the low-mass, metal-poor satellites of M31 it is possible to extend the parameter space for empirical calibrations between the C/M ratio and the metallicity in this poorly constrained regime. This is a crucial step for the upcoming NIR imaging era of JWST/E-ELT (when it will be possible to resolve luminous AGB stars for galaxies out to 20 Mpc) and for large NIR spectroscopic campaigns for AGB stars (e.g. VLT/MOONS).

Understanding the extreme AGB stars in the LMC

F. Dell’Agli, P. Ventura, D. A. Garcia-Hernandez, C. Rossi S5-05

The Large Magellanic Cloud represents one of the best targets to understand the role of Asymptotic Giant Branch stars as dust polluters in the Universe. Spitzer observations of LMC AGB stars outline the presence of a sample of sources, called "extreme", severely obscured, whose nature is still debated. We provide an interpretation of these objects on the bases of theoretical models of dust formation in the winds of AGBs. The reddest ob- jects are identified as carbon stars in the latest thermal pulses. The excursion of massive M-stars experiencing hot bottom burning in the color-color and color-magnitude diagrams in the infrared bands is also commented.

114 Dust Composition and Mass Loss Return from a Luminous Blue Variable R71 in the LMC

S. Guha Niyogi, M. Min, M. Meixner, L.B.F.M. Waters, J. Seale, A.G.G.M. Tielens S5-06

We present an analysis of mid and far infrared (IR) spectrum and spectral energy distribu- tion (SED) of the luminous blue variable (LBV) R71 in the Large Magellanic Cloud (LMC). We compiled all the available photometric and spectroscopic observational fluxes from various telescopes for a wide wavelength range (0.36 - 250 µm). We noted 9 spectral features in the dust shell of R71 and the potential mineral carriers of these features. We computed our model spectrum by using 3-D radiative transfer code MCMax. From our model calculation, we find out that dust is dominated by amorphous silicates, with some crystalline silicates, metallic iron and a very tiny amount of Polycyclic Aromatic Hydro- carbon (PAH) molecules. The presence of both silicates and PAHs indicate that it has a mixed chemistry. We derived a dust mass of 0.01 M , from which we arrive at a total ejected mass of ∼ 5 M . Based on our analysis on R71, we speculate that LBVs may be an important dust source in the ISM of the LMC.

PIONIERing diameter measurements of globular cluster giants

J. Hron, H. Boffin, J.-B. Le Bouquin, T. Lebzelter, C. Paladini, I. Soszynski, J.-P. Berger, M. Wittkowski S5-07

We present an attempt to resolve one of the brightest long period variables in the globular cluster 47 Tuc with the PIONIER instrument at the VLTI in the H-band. Based on model atmospheres and observations of local LPVs the predicted visibilities were about 0.9, i.e. at the limit of feasibility with PIONIER. Unfortunately, the observations show that the star is unresolved with an upper limit for the UD-diameter in the H-band of 0.44 mas. We compare this with the predictions and discuss requirements for resolving this star in 47 Tuc.

115 Evolved stars in Milky Way dSphs probed with Spitzer

S. Lianou, P. Barmby, M. L. N. Ashby, J. L. Hora, K. D. Gordon, T. H. Jarrett, H. Shiu S5-08

Low- and intermediate-mass evolved stars are important to our understanding of the in- terstellar medium enrichment process within galaxies. We present results on the low- and intermediate-mass evolved stars detected in Milky Way dwarf spheroidal galaxies imaged in the mid-infrared with Spitzer. We estimate the mass-loss rates of the AGB stars in our sample galaxies, and we compare them with mass-loss rate estimates in other galaxies. We discuss our findings in relation to the interstellar medium content of dwarf spheroidal galaxies.

The first AGBs of the Galaxy

T. Masseron S5-09

Carbon-rich metal-poor stars are now accepted to be mass-transferred binary members of the first generation of stars. Indeed, the peculiar chemical fingerprints revealed by their spectra represent a unique opportunity to study their now extinct progenitor (basically all low-metallicity stars with M > 0.8 M ) and the early stages of the Galaxy. In the context of the current existing high quality spectrographs and large surveys, I will focus on the techniques used to analyse such challenging spectra. In particular, I will focus on their peculiar atmosphere structure and their molecular features. In parallel, I will also show how the abundances derived from these objects tell us about the physics, nucleosynthesis of the first generations of AGB stars.

Mass loss from metal-poor stars

I. McDonald S5-10

Mass loss from metal-poor AGB stars has driven the chemistry of today’s Universe, yet most observations have concentrated on nearby, metal-rich objects or "metal- intermediate" objects in the Magellanic Clouds. Here, I will summarise our recent re- search into stars up to 250 times more metal-poor than the Sun. I will look at how mass loss before the AGB phase can be important; how and when dust production starts, and its relationship to pulsation, stellar luminosity and metallicity; the dust condensation se- quence in metal-poor stars; and present the initial interpretation of our ALMA observa- tions of CO outflows from metal-poor stars.

116 Spectroscopic Surface Brightness Fluctuations: Investigating RSG and AGB Stars in Unresolved Stellar Populations

M. Mitzkus, S. Dreizler, M. M. Roth S5-11

The parameter range of observable AGB stars in resolved stellar populations is limited. Therefore unresolved stellar populations are an important observational target to com- plete our understanding of AGB stars. It has long been known that red and infrared Sur- face Brightness Fluctuations (SBFs) are dominated by AGB stars and multi-band SBF measurements have been proposed to probe AGB evolution. We go one step further and develop Spectroscopic SBFs: these will combine the physical information of stellar absorption lines with the diagnostic power of SBFs. With first tests on ARGUS-IFU data we demonstrated that the SBF method yields useful results in principle. Due to its high sensitivity, large FoV and spatial sampling MUSE is the first instrument that allows to fully use the SBF method for science analysis. Spectroscopic SBFs have the potential to address numerous issues in the evolution of stars in bright, rare stellar phases.

Radiative Transfer Modelling of Dust in IRAS 18333–2357: The only planetary nebula in the metal-poor globular cluster M22

C. Muthumariappan, M. Parthasarathy, Y. Ita S5-12

We report results from our 1-D radiative transfer modelling of dust in the hydrogen- deficient PN IRAS 18333–2357 in M22 using archival UV, optical and IR data. An archival Spitzer spectrum shows several aromatic infrared bands indicating a carbon-rich dust shell. The spectral energy distribution is well fit by a model which includes compression of the nebula by its interaction with the Galactic Halo gas. The model shows a significant amount of cold dust with temperature 50 K present at the outer edge of the nebula. A large amount of mid-IR excess emission is also present which have originated from the thermally fluctuating grains with size ∼ 12 Å in the UV field of the hot central star. The − mass of this grain population is (1.2 ± 0.73) × 10 3 M which is comparable to the mass of the thermal equilibrium grains. The derived dust-to-gas mass ratio is 0.3 ± 0.21 and the bolometric luminosity is 1700 ± 1230 L . We propose that the progenitor of this PN had evolved from an early stellar merger case and the hydrogen-deficient nebula results from a late thermal pulse.

117 Infrared Variable Stars in the Small Magellanic Cloud

E. Polsdofer, J. Seale, M. Sewilo, U. Vijh, M. Meixner, M. Marengo, M. Terrazas S5-13

We present our results and source list of variable sources in the Small Magellanic Cloud (SMC). The data are taken from "Surveying the Agents of Galaxy Evolution in the Tidally- stripped, Low Metallicity SMC" (SAGE-SMC) and the "Spitzer Survey of the Small Mag- ellanic Cloud" (S3MC), taken over three different epochs separated in time from each other by several months to a year. Thermal infrared variable sources are identified using a combination of the Infrared Array Camera (IRAC) 3.6, 4.5, 5.8 and 8.0 µm bands and the Multiband Imaging Photometer for Spitzer (MIPS) 24 µm band. An error-weighted flux difference between three intervals of data is used to assess the variability. Of the 8 million sources in the SAGE catalog, we identify ∼ 800 that meet our variability criteria of at least 3σ in two neighboring bands. We matched to the literature to find carbon-rich AGB stars make up the majority (61%) of our variable sources, with about a third of all sources being also classified as extreme AGB stars. We find populations of oxygen-rich AGB (8.6%), red supergiant stars (2.8%), red giant branch stars (< 1%), Cepheid vari- able stars (8.6%), young-stellar objects (5.8%), background galaxies (1.2%) and early type stars (2.8%).

The SAGE-Var IR Variability Survey: First Results

D. Riebel, S. Srinivasan, M. Boyer, B. Sargent, M. Meixner S5-14

We present the first results from the SAGE-Var program (Riebel et al., 2014, in prep), a follow-on program to the Spitzer legacy program Surveying the Agents of Galaxy Evo- lution (SAGE; Meixner et al., 2006). We obtained 4 epochs of photometry at 3.6 & 4.5 µm covering the bars of the Large and Small Magellanic Clouds (LMC and SMC, respec- tively) in order to probe the variability of extremely red sources missed by ground based variability surveys conducted at visible wavelengths. Our 6 total epochs of observations allow us to probe infrared variability on 15 different timescales ranging from ∼ 20 days to ∼ 5 years. Out of a full catalog of 1,717,556 (LMC) and 457,760 (SMC) objects, we identify 3726 (LMC) and 1283 (SMC) variable objects, 1888 (LMC) and 851 (SMC) of which have no known counterpart in the MACHO (Alcock et al., 1997) or OGLE (Udalski et al., 1997) microlensing surveys.

118 The SAGE-Spec Spitzer Legacy programme: Point source classification of Spitzer-IRS staring mode targets in the Small Magellanic Cloud

P. M. E. Ruffle, F. Kemper, O. C. Jones, G. C. Sloan, K. E. Kraemer, P. M. Woods, V. Antoniou, M. L. Boyer, E. Lagadec, M. Matsuura, I. McDonald, J. M. Oliveira, B. A. Sargent, M. Sewilo, S. Srinivasan, R. Szczerba, J. Th. van Loon, K. Volk, A. A. Zijlstra S5-15

We have searched the Spitzer Space Telescope data archive for InfraRed Spectrograph (IRS) staring-mode observations of the Small Magellanic Cloud (SMC) within the footprint of the SAGE-SMC Spitzer Legacy programme. We selected the genuine point sources for this sample by correlating the spectrum positions with point sources in the relevant photometric catalogues. We classify these point sources using a decision tree method of object classification, based on infrared spectral features, continuum and spectral energy distribution shape, bolometric luminosity, cluster membership and variability information into Asymptotic Giant Branch (AGB) stars, young stellar objects (YSOs), post-AGB stars, Red Supergiants (RSGs), objects only showing stellar photospheres, background galax- ies, planetary nebulae (PNe), HII regions and other objects, some of which remain un- classified. Our classifications of these bright infrared point sources provide spectral pro- files for each type of star in the SMC. We use these classifications to improve deductions about the stellar populations of the SMC and the success of photometric classification methods. In particular, we compare these spectroscopic results with those for the same objects using photometric classification schemes. We discuss the robustness of relying on photometric colours when identifying stars and the implications of misidentification when calculating dust inputs to the ISM. Note: Paul Ruffle passed away on November 21, 2013.

119 Detecting Long period variables in M33 galaxy using UKIRT-WFCAM images

M. Saberi, A. Javadi, J. van Loon, H. Khosroshahi S5-16

We have conducted a near-infrared monitoring campaign at the UK InfraRed Telescope (UKIRT), of the Local Group spiral galaxy M33. The observation had been done with Wide Field camera (WFCAM) which covers the spiral arms of M33 galaxy. The main aim was to identify the stars at the last stage of their evolution which luminosity is more directly related to the birth mass compared to main sequence stars, therefore detecting variable AGB stars is a powerful tool in reconstructing the star formation history of a galaxy. The most extensive dataset is obtained in the K-band with WFCAM instrument for the 15 kpc region, this contains disc and spiral arms. These data have been taken from 2005 to 2007, were complemented by J-band and H-band images. Photometry was obtained for 403,734 stars in this region; of these, 4643 stars were found to be variable, most of which are asymptotic giant branch (AGB) stars. Our data were matched to optical catalogues of variable stars and to mid-infrared photometry from the Spitzer Space Telescope. Most dusty AGB stars had not been previously identified in optical variability surveys, and our survey is also more complete for these types of stars than the Spitzer survey.

Spitzer-IRS Studies of the Properties of Circumstellar Dust around Oxygen-Rich Asymptotic Giant Branch and Red Supergiant Stars

B. Sargent, S. Srinivasan, A. Speck, K. Volk, F. Kemper, W. Reach, E. Lagadec, J.-P. Bernard, I. McDonald, M. Meixner, G. C. Sloan, O. Jones S5-17

We analyze the dust emission features seen in Spitzer Space Telescope Infrared Spec- trograph (IRS) spectra of Oxygen-rich (O-rich) asymptotic giant branch (AGB) and red supergiant (RSG) stars. The spectra come from the Spitzer Legacy program SAGE- Spectroscopy (PI: F. Kemper) and other archival Spitzer-IRS programs. The broad 10 and 20 micron spectral emission features attributed to amorphous dust of silicate compo- sition show evidence for systematic differences in the central wavelength of both emission features between O-rich AGB and RSG populations. GRAMS radiative transfer modeling of the AGB and RSG stars suggests that the central wavelength differences are due to differing dust properties. We show recent modeling using different dust opacities to in- vestigate differences in dust composition, size, shape, etc. that might be responsible for these spectral differences. We explore how differing environments affect the RSG and O-rich AGB stars’ dust differently.

120 The Sagittarius Dwarf Spheroidal Galaxy and M54 in the 1612 MHz OH line

L. O. Sjouwerman, M. J. Claussen S5-18

We report on our search for 1612 MHz OH masers toward Sag DEG/M54 with the VLA.

The Bulge Asymmetries and Dynamic Evolution project

L. O. Sjouwerman, Y. M. Pihlstrom; and the BAaDE collaboration S5-19

We will present the first results of a VLA survey for the SiO maser in MSX color selected sources. With a novel calibration scheme we obtain a 70% detection rate with minimal observing overhead in the first 3500 sources observed out of a total observing sample of over 20000 objects. The main objectives of this survey include 1) Statistics of SiO masers in the Galaxy, 2) Galactic dynamics and detailed Galactic structure, 3) VLBI proper mo- tions of Galactic orbits and structure of individual stars, and 4) SiO maser characteristics and stellar and circumstellar properties.

Which dust from AGBs?

P. Ventura S5-20

Asymptotic Giant Branch stars are believed to be one of the main contributors of dust in the Universe. In this contribution we show how the description of the dust formation process turns out to be extremely sensitive to the modelling of the AGB phase, particularly to the treatment of the convective instability. We focus on the dichotomy between low mass stars, that produce mainly carbon dust, and the AGBs experiencing Hot Bottom Burning, dominated by silicates. The trend with metallicity is discussed.

Did globular clusters care about AGB stars?

Y. Wang, F. Primas, C. Charbonnel S5-21

In recent years, multiple stellar populations have been identified in Galactic globular clus- ters (GCs), with different scenarios being debated for their origin (namely the AGB and the Fast Rotating Massive Stars models). In this context, the core of our project is to try to disentangle between first and second generation stars based on their chemical prop- erties, in order to probe these models. Here we present a preliminary chemical analysis of a new sample of AGB stars in NGC 2808 observed at the VLT with FLAMES, in order to further investigate the recent finding that no Na-rich stars are found on the AGB.

121 Modelling the sequences of luminous pulsating red giants

P. R. Wood S5-22

Long-term photometric monitoring over the last two decades by microlensing experiments such as MACHO and OGLE has provided data which has revolutionized our understand- ing of red giant variability. The results of these surveys show that the luminous red giants fall on approximately ten period-luminosity (PL) sequences of different origin. Eight of these sequences are almost certainly of pulsation origin. I will discuss the nature of these pulsation sequences as revealed by OGLE and MACHO data and I will describe the latest attempts to model them.

Exciting fates of massive AGB stars in star clusters

S. Zhukovska, M. Petrov S5-23

There is a puzzling discrepancy between the mass distribution of parent AGB stars of oxygen-rich grains predicted by dust evolution models and that deduced from presolar grain studies. Isotopic anomalies measured in these grains indicate that they all originate from low-mass AGB stars, while a contribution from massive AGB stars predicted by the models is missing. Such models do not account that massive AGB stars can be members of star clusters and this may affect formation and survival of grains. Using models of dy- namical evolution of star clusters at solar galactocentric radius with a large range of initial masses, we estimate the fraction of massive AGB stars that evolve in clusters. These AGB stars are irradiated by the intracluster ultraviolet radiation field created by main se- quence cluster members, which is 10−100, in some cases 104 times stronger than the interstellar radiation field. We will discuss the impact of the star cluster environment on the circumstellar shells of massive AGB stars.

122 Session 6: Perspectives

Improving Herschel imaging datasets

M. Mečina, A. Mayer, R. Ottensamer, A. Luntzer, F. Kerschbaum S6-01

The Herschel Space Observatory enabled a deep and detailed look into the far-infrared universe and even though the mission ended in May 2013, the rich archive is full of data to be analysed. The Herschel data reduction pipelines have progressed to give good results for most types of observations, but for other, more specialized programmes, improved im- age reconstruction tools and methods need to be applied to fully exploit the telescope’s unique sensitivity and spatial resolution. This is the case for post-main-sequence objects observed with Herschel/PACS as part of the MESS sample. Here, the standard pipeline as well as most map-makers cannot handle the bright central source surrounded by faint dust emission well. We compare the six standard map-making tools for Herschel ob- servations and show how an improved astrometry can produce better maps. Our data processing steps can be applied to the standard pipeline as well as to external mappers based on inverse techniques.

123 CONFERENCE INFORMATION

Technical information for speakers: To minimize "overhead" during the meeting by switching of laptops, we kindly ask you to bring your presentation on a memory stick to copy it onto the computer system of the lecture hall well before your talk. We will provide both a Windows PC and a Mac. A LOC member will assist you during the coffee breaks and before the morning and the afternoon sessions. If you wish to use an overhead pro- jector please let us know in advance.

Name badges: Admission of participants to all sessions is by the conference name badge only. Participants are requested to wear their name badge at all times.

Posters: Posters are on display in the foyer of the lecture hall during the whole meeting. Authors are asked to be available at their posters for discussion during the breaks. Each poster board is numbered, the corresponding numbers are given in this abstract booklet. LOC members will be around to help you find the location of your poster. It’s best to mount your poster before the talks begin on Monday morning. Please remove it until the end of the meeting.

124 SOCIAL PROGRAM

WALKING TOUR "VIENNA AT FIRST GLANCE" This orientational tour gives you a nice overwiew over the city. Beside the main sights in the city center, like the Imperial Palace and St. Stephan’s Cathedral, we also dive into more off-the-beaten-track parts of the city with its small streets and hidden courtyards. At every corner there is a part of our 2000 year history to be found starting with the Romans up to modern day life. MONDAY, 18:30-20:30, leaving in front of the campus, and ending at St. Stephan’s Cathedral. www.viennawalks.com

EXCURSION TO THE WACHAU VALLEY During the ship cruise up the river Danube you will have the chance to taste fine wines of the region and learn about the history of the beautiful valley. Afterwards our busses will bring you to the castle ruin of Aggstein with its breath-taking view from 300m above the winding river Danube. A small lunch packet is also included. WEDNESDAY, 12:30-19:00, leaving in front of the campus

CONFERENCE DINNER The informal dinner will take place at the Vienna Observatory. Guided tours through the observatory will be offered during the dinner. PLEASE NOTE: Smoking is not allowed in the whole observatory building. THURSDAY, starting at 19:00, Türkenschanzstrasse 17, 1180 Vienna (see the "How to get there" section)

125 HOW TO GET THERE

University Campus Spitalgasse 2 1090 Vienna We are located in Court 2.6

The University Campus is easily reachable by the following lines of public transport: Tram Nr. 5 (Lazarettgasse), 43 and 44 (Lange Gasse), within a few minutes walking distance: 37, 38, 40, 41, 42 (Spitalgasse/Währinger Straße), as well as Bus Nr. 13A.

Going from the Campus to the Observatory: take the Tram line 40 or 41 from Spital- gasse/Währingerstrasse heading towards Gersthof or Pötzleinsdorf. Leave at Aumann- platz at its west end and walk uphill (Türkenschanzstraße 17).

126 Location of the observatory, where the conference dinner will take place.

127 GENERAL INFORMATION ON PUBLIC TRANSPORT IN VIENNA: Vienna has a very good and safe public transport system consisting of 5 underground lines and a large number of tram lines and buses. The tram lines and buses typically operate between 6:00 and 00:00, the underground between 5:00 and 0:30. During the night special night buses are running. Tickets for the public transport can be bought in underground stations, at ticket machines, at several newspaper stores and also directly in buses and tramways. A single ticket costs EUR 2.20 (EUR 2.60 if you buy it in the bus or tram). You can use it for one trip in one direction including changes. Tickets bought in advance must be punched in a blue ticket cancelling machine in the tram or bus or at the barrier before you board the underground train. There is also a one week ticket (Monday to Sunday) for EUR 16.20. Children under the age of six travel free of charge, between 6 and 15 they have to pay the half price. http://www.wienerlinien.at

EMERGENCY INFORMATION: Emergency numbers: European emergency telephone number 112, fire brigade 122, police 133, medical emergency 144 Pharmacy: Tiger Apotheke, Alser Strasse 12 LOC members: +43 650 7285666 (Lebzelter), +43 664 4561316 (Hron), +43 664 8175060 (Kerschbaum)

OTHER PRACTICAL INFORMATION: Cell phones: You are kindly requested to have your cell phone turned off while in any of the conference sessions. Thank you for your co-operation. Internet connection: There is a WLAN access in the foyer of the lecture hall. A further internet access will be provided in a nearby terminal room. You will find a WLAN access code in your conference bag. Parking: There is no possibility to park your car inside the campus. Around the cam- pus there are only short term parking areas (maximum allowed time 2 hours) and you require a parking ticket. We recommend to leave your car at the hotel and use the public transport or walk. Usually you find some parking space close to the observatory free of charge. Smoking is not permitted inside in the campus buildings or the observatory building. Taxi: call 31300, 40100, or 60160

128 HUNGRY? This is a non-complete list of nearby places for dining: Inside the campus (Austrian type): Bierheuriger Zum Gangl: Hof 1 Salettl: Hof 1 Stiegl-Ambulanz: Hof 1 Uni-Bräu: Hof 1 Outside the campus: Adam: Austrian; Florianigasse 2 Cafe Weimar: Austrian; Währinger Strasse 68 McDonald’s: Fast Food; Josefstädter Strasse 73 Pizzeria Guiliano: Italian; Tendlergasse 3 Rembetiko: Greek; Porzellangasse 38 Safran: Pakistani; Garnisongasse 10 Stadtheuriger - Zum narrischen Kastanienbaum: Austrian; Strozzigasse 36 Tokyo Running Sushi: Japanese; Laudongasse 34 Tunnel: cheap student restaurant; Florianigasse 39

129 130 Participants

Aringer, Bernhard Burger, Christoph Department of Astrophysics, Uni Vienna Institut für Astrophysik, Uni Wien [email protected] [email protected]

Arroyo Torres, Belén Cherchneff, Isabelle Universidad de Valencia Department of Physics, University of Basel [email protected] isabelle.cherchneff@unibas.ch

Baier, Angela Chiavassa, Andrea Institut für Astrophysik, Uni Wien Observatoire de la Cote d’Azur [email protected] [email protected]

Baum, Hubert Chun, Sang-Hyun Institut für Astrophysik, Uni Wien Yonsei University Observatory [email protected] [email protected]

Baumgartner, Verena Clayton, Geoffrey Institut für Astrophysik, Uni Wien Louisiana State University [email protected] [email protected]

Bladh, Sara Cox, Nick Uppsala University KU Leuven [email protected] [email protected]

Blommaert, Joris Cristallo, Sergio Astronomy and Astrophysics RG, VU Brussel INAF - Osservatorio Astronomico di Teramo [email protected] [email protected]

Bono, Giuseppe Danilovich, Taissa University of Rome Tor Vergata Chalmers University of Technology [email protected] [email protected]

Boyer, Martha Davis, Philip NASA Goddard Space Flight Center Institut d’Astronomie et d’Astrophysique, ULB [email protected] [email protected]

Bozkurt, Zeynep De Beck, Elvire Ege University Max-Planck Institut für Radioastronomie [email protected] [email protected]

Brunner, Magdalena De Nutte, Rutger Institut für Astrophysik, Uni Wien KU Leuven - Institute of Astronomy [email protected] [email protected]

131 De Smedt, Kenneth Goswami, Aruna Instituut voor Sterrenkunde, KULeuven Indian Institute of Astrophysics [email protected] [email protected] de Vries, B.L. Groenewegen, Martin Stockholm University Royal Observatory of Belgium [email protected] [email protected]

Dell’Agli, Flavia Guzman, Lizette University of Rome, La Sapienza ESO fl[email protected] [email protected]

Do, Hoai Haika, Anneliese Paris Observatory Institut für Astrophysik, Uni Wien [email protected] [email protected]

Engels, Dieter Hamren, Katherine Hamburger Sternwarte University of California Santa Cruz [email protected] [email protected]

Eriksson, Kjell Hartig, Erich Uppsala University Institut for Astrophysics [email protected] [email protected]

Feast, Michael Hartig, Julia UCT/SAAO Institut für Astrophysik, Uni Wien [email protected] [email protected]

Galan, Cezary Haubois, Xavier Nicolaus Copernicus Astronomical Center Observatoire de Paris [email protected] [email protected]

Gezer, Ilknur Hillen, Michel Institute of Astronomy KU Leuven KULeuven [email protected] [email protected]

Girardi, Leo Hinkle, Kenneth Osservatorio Astronomico di Padova NOAO [email protected] [email protected]

Gobrecht, David Höfner, Susanne Universität Basel Dept. of Physics & Astronomy, Uppsala University [email protected] [email protected]

Goldman, Steve Homan, Ward Keele University KULeuven [email protected] [email protected]

Goldmann, Christoph Hren, Andreas Institut für Astrophysik, Uni Wien Institut für Astrophysik, Uni Wien [email protected] [email protected]

Gonneau, Anaïs Hron, Josef Strasbourg Astronomical Observatory Institut für Astrophysik, Uni Wien [email protected] [email protected]

132 Humphreys, Elizabeth Kerschbaum, Franz ESO Institut für Astrophysik, Uni Wien [email protected] [email protected]

Huxor, Avon Kerschbaum, Nikolaus Astronomisches Rechen-Institut Institut für Astrophysik, Uni Wien [email protected] [email protected]

Izzard, Robert Khouri, Theo Argelander-Institut für Astronomie, University of Bonn Anton Pannekoek Inst. for Astronomy - Uni Amsterdam [email protected] [email protected]

Jones, Olivia Klavins, Atis JBCA, University of Manchester Institute of Astronomy University of Latvia [email protected] [email protected]

Jönsson, Henrik Lagadec, Eric Lund Observatory Cornell University, Department of Astronomy [email protected] [email protected]

Jorissen, Alain Lambert, Julien ULB - Institut d’Astronomie Lund Observatory [email protected] [email protected]

Josselin, Eric Lebzelter, Thomas LUPM - University Montpellier II Institut für Astrophysik, Uni Wien [email protected] [email protected]

Jung, DooSeok Lewis, Brian Yonsei University Arecibo Observatory [email protected] [email protected]

Justtanont, Kay Lianou, Sophia Chalmers University of Technology Western University [email protected] [email protected]

Kamath, Devika Liljegren, Sofie Institute of Astronomy, KU Leuven Uppsala University [email protected] sofi[email protected]

Kang, Minhee Lombaert, Robin Yonsei University Instituut voor Sterrenkunde - KU Leuven [email protected] [email protected]

Karakas, Amanda Luntzer, Armin Australian National University Institut für Astrophysik, Uni Wien [email protected] [email protected]

Karinkuzhi, Drisya Lykou, Foteini Indian Institute Of Astrophysics University of Vienna [email protected] [email protected]

Keller, Denise Macdonald, Daniel Max-Planck-Institut für Radioastronomie Macquarie University [email protected] [email protected]

133 Maciel, Walter Mohamed, Shazrene University of Sao Paulo South African Astronomical Observatory [email protected] [email protected]

Maercker, Matthias Montargès, Miguel Onsala Space Observatory LESIA/Observatoire de Paris [email protected] [email protected]

Marengo, Massimo Müller, Isolde Iowa State University Institut für Astrophysik, Uni Wien [email protected] [email protected]

Marigo, Paola Muthumariappan, Chinnathambi Dept. of Physics and Astronomy, University of Padova Indian Institute of Astrophysics [email protected] [email protected]

Masseron, Thomas Mutschke, Harald IoA, Cambridge Astrophysical Institute and University Observatory [email protected] [email protected]

Matthews, Lynn Nanni, Ambra MIT Haystack Observatory Keele University [email protected] [email protected]

Mattsson, Lars Nowotny, Walter Nordita (Stockholm Univ. & KTH Royal IoT) Institut für Astrophysik, Uni Wien [email protected] [email protected]

Mayer, Andreas O’Gorman, Eamon Institut für Astrophysik, Uni Wien Chalmers University of Technology [email protected] [email protected]

McDonald, Iain Ohnaka, Keiichi University of Manchester Max Planck Institute for Radio Astronomy [email protected] [email protected]

Mečina, Marko Olofsson, Hans Institut für Astrophysik, Uni Wien Onsala Space Observatory [email protected] [email protected]

Meingast, Stefan Ottensamer, Roland Institut für Astrophysik, Uni Wien Institut für Astrophysik, Uni Wien [email protected] [email protected]

Meixner, Margaret Öttl, Silvia Space Telescope Science Institute Institute for Astro- and Particle Physics [email protected] [email protected]

Menzies, John Paladini, Claudia SAAO ULB [email protected] [email protected]

Mitzkus, Martin Palmerini, Sara Leibniz-Institut für Astrophysik Potsdam (AIP) LNS - INFN [email protected] [email protected]

134 Perrin, Guy Schobesberger, Thomas Observatoire de Paris / LESIA Institut für Astrophysik, Uni Wien [email protected] [email protected]

Pham, Nhung Schwab, Josiah Institute for Nuclear Science and Technology UC Berkeley [email protected] [email protected]

Phillips, Neil Shingles, Luke Joint ALMA Observatory / ESO Australian National University [email protected] [email protected]

Posch, Thomas Sjouwerman, Lorant Institut für Astrophysik, Uni Wien NRAO [email protected] [email protected]

Ramos-Larios, Gerardo Sloan, Gregory C. Instituto de Astronomia y Meteorologia Cornell University [email protected] [email protected]

Ramstedt, Sofia Smith, Christina Uppsala University JBCA, University of Manchester sofi[email protected] [email protected]

Rau, Gioia Srinivasan, Sundar Institut für Astrophysik, Uni Wien Inst. of Astronomy & Astrophysics, Academia Sinica [email protected] [email protected]

Renzini, Alvio Stancliffe, Richard INAF, Osservatorio Astronomico di Padova Argelander Institute for Astronomy [email protected] [email protected]

Riffel, Rogério Straniero, Oscar IF-UFRGS INAF-Osservatorio di Teramo riff[email protected] [email protected]

Rosenfield, Philip Sundl, Maria Department of Physics and Astronomy, Uni Padova Institut für Astrophysik, Uni Wien philip.rosenfi[email protected] [email protected]

Ryde, Nils Sung, Eon-Chang Lund University Korean Astronomy and Space Science Institute [email protected] [email protected]

Saberi, Maryam Tamayama, Masaki Chalmers University Tohoku University [email protected] [email protected]

Sabin, Laurence Teyssier, David Universidad de Guadalajara ESAC/ESA [email protected] [email protected]

Schneider, Raffaella Till, Anna INAF/Osservatorio Astronomico di Roma Institut für Astrophysik, Uni Wien raff[email protected] [email protected]

135 Trejo, Alfonso Wittkowski, Markus ASIAA ESO [email protected] [email protected]

Trippella, Oscar Wong, Ka Tat INFN, Section of Perugia Max Planck Institute for Radio Astronomy [email protected] [email protected]

Uttenthaler, Stefan Wood, Peter Department of Astrophysics, Vienna Australian National University [email protected] [email protected]

Van de Sande, Marie Zhukovska, Svitlana Instituut voor Sterrenkunde - KU Leuven MPIA [email protected] [email protected]

Van Eck, Sophie Institut d’Astrophysique, Universite Libre de Bruxelles [email protected]

Van Winckel, Hans KULeuven [email protected]

Ventura, Paolo INAF - Observatory of Rome [email protected]

Vlemmings, Wouter Chalmers University of Technology [email protected]

Wallner, Stefan Institut für Astrophysik, Uni Wien [email protected]

Wang, Yue European Southern Observatory [email protected]

Weber, Conny Institut für Astrophysik, Uni Wien [email protected]

Whitelock, Patricia SAAO & UCT [email protected]

Wing, Robert Ohio State University [email protected]

Winters, Jan Martin IRAM [email protected]

136 Sponsors

The conference organisers gratefully acknowledge the support of the following sponsors:

THE ROBERT F. WING SUPPORT FUND AT OHIO STATE UNIVERSITY

THE FACULTY OF EARTH SCIENCES, GEOGRAPHY AND ASTRONOMY

THE AUSTRIAN SCIENCE FUND

137