Talks Antofagasta, March 1-4, 2016 1

XIII Annual Meeting of the Chilean Astronomical Society Book of abstracts - Talks Antofagasta, March 1-4, 2016 1

Claudia Agliozzo Universidad Nacional Andrés Bello

A tale of the mass-loss of the magellanic LBV R127

During their lifetime, Luminous Blue Variable stars (LBVs) must rapidlyexpel their H envelope, with the highest mass-loss rates (> 10^(-5) M_sun/yr), in order to evolve into Wolf-Rayet stars.However, the physical mechanism underlying the mass-loss is not yet understood.I present our extraordinary multiwavelength dataset of R127, a famousLBV in the Large Magellanic Cloud, widely observed in the past at visiblewavelengths. Our dataset comprises high-resolution centimetre ATCA and submillimetre ALMA data, in addition to new high-spectral resolution optical data acquired with the instrument MIKE at Magellan II telescope.As shown by the different spectral features detected, the mass-loss ishighly complex, with signatures of different episodes, such as have beenseen in previous spectroscopic observations and in the galactic prototypeLBV AG Carinae. We newly discover that from theinner to the outer regions, the stellar wind changes geometry.With all our data together, the picture seems much clearer: theasymmetric morphology of the wind and of the circumstellar nebula aremore likely due to external factors than intrinsic asymmetriesof the mass-loss. I will discuss different scenarios.We don't know yet how common this behaviour is in galactic and magellanic LBVs. However, noticeably, the geometry of the nebula resembles that of Eta Carinae and of the blue-supergiant progenitor of Supernova 1987A.

Gustavo Aguayo Universidad de Concepción

Optical study of the Be star Mu Centauri

We present an optical study of the Be star Mu Centauri, this study was developed using spectroscopic data taken with CHIRON and CORALIE spectrograph, there were measured important parameters of some lines located at the optical range as equivalent width and peak separation, also correlations between equivalent widths of some lines were found and are presented here. The peak separation was used to constrain the extension of the line forming regions and this work is also presented in this poster. Also we present in this poster visual photometry of this star covering the same lapse that the spectra, the result of the correlation between equivalent width of H alpha and magnitude is shown below.

Claudia Aguilera Pontificia Universidad Católica

Lithium enrichment in red giant branch stars

Lithium (Li) is easily destroyed inside low mass. During the red giant branch phase the surface Li abundance decreases even further by dilution, but a small number of giants is known to be Li-rich. This is unexpected and it cannot be accounted for by canonical stellar evolution. One of the possible explanations for these atypical giants is the engulfment of a planet or brown dwarf by the star. In this work, we model the evolution of lithium abundance post first dredge up including the accretion of a sub-stellar mass companion. We consider a wide range of stellar and companion masses and initial lithium abundances, stellar metallicities and time of engulfment, including the most optimistic choices that would produce the highest superficial Li abundances. We find that even with the best possible conditions, i.e., a companion with supermeteoritic Li abundance that produces a maximum signature of A(Li) ∼ 2.7, the accretion of a sub-stellar mass companion alone cannot explain all the observed lithium rich giants andthus it seems necessary to include internal production of the light element plus additional non-canonical physics, such as an extra-mixing process.

Alba Aller Universidad de Valparaiso

Search for binary central stars of planetary nebulae: exploding archival data

With the new binary central stars (CSs) identified in the last years, binary interactions have become the main proposed mechanism to explain the complex morphologies seen in planetary nebulae (PNe). There are around 50 binary CSs detected so far. However, this number remains very small as compared to the more than 3000 known PNe in the Milky Way. In this context, we are involved in a project to study how binary interaction processes influence the shape of PNe. Archival data offer a great opportunity to search for new candidates of binary CSs since surveys like, e.g., Catalina, ASAS and OMC provide light curves of a large number of objects in a long timespan. We are exploding these surveys to search for new candidates that will be subsequently followed-up by means of multi-epoch photometric and spectroscopic observations. In this talk, we will summarize the goals of this project and show the first results.

Simón Ángel Pontificia Universidad Católica

Characterisation of stellar populations in the CFHTLS Deep fields

Combining the information of the CFHTLS (Gwyn 2011) and WIRDS (Bielby et al. 2012) surveys, I constructed multiwavelength catalogues for the four Deep CFHTLS fields. Using the selection tool presented in Muñoz et al. (2014), I produced a clean and deep (limiting magnitude in r ~ 26) subset of stars. Colour, magnitude, metallicity, and distance distributions have been studied, using for the latter, the methods presented in the Milky Way Tomography series of papers (Jurić et al. 2008, Ivezić et al. 2008, Bond et al. 2010) and in Sesar et al. (2011). In this talk, I will present the dataset and the distributions aforementioned, along with comparisons with the Besançon model of stellar population synthesis of the Galaxy (Robin et al. 2003).

Rodolfo Angeloni Gemini Observatory

The Sanduleak's star in the Large Magellanic Cloud

Sanduleak's star is a variable emission-line object in the Large Magellanic Cloud. It was discovered in 1977 and, already in the early 80's, a similarity with eta Carinae and SN 1987A was proposed on the basis on IUE observations which indicated episodic mass outflow, extreme departures from normal cosmic values of nitrogen relative to carbon and oxygen, and an electron temperature which is hard to reconcile with pure photo-ionization models. Sanduleak's star came abruptly back on stage in 2011, when we discovered that it powers a giant, highly-collimated bipolar jet extending over almost 15 pc: to our knowledge, it is the largest stellar jet discovered so far, and the first one clearly resolved beyond the Milky Way. In this contribution we present our follow-up observations of Sanduleak's star obtained over the last few years. In particular: HST-WFC3 narrow-band images, that allow us to resolve the spectacular inner nebula; Magellan-FIRE and MMIRS near-infrared spectra, which give insight on the symbiotic character of the central binary; Magellan-MIKE high-resolution optical spectra, that further constraint the kinematics, chemistry and energetics of the overall system. We thus discuss the nature of Sanduleak's star and place it in the general context of the late stages of stellar evolution, by also highlighting some tentative links with the Intermediate-Luminosity Optical Transients.

Javier Arenas Pontificia Universidad Católica de Valparaiso

Can pulsar glitches be explained by "starquakes"?

Pulsars are the best clocks known in universe, with very precisely periodic pulses due to the rotation of a neutron star with a strong dipolar magnetic field. The pulses slow down progressively, due to the release of rotational energy. In addition, there are timing irregularities, the most prominent of which are "glitches", sudden spin-up events, in which about 1 % of the spin-down is "recovered".There are two main mechanisms discussed in the scientific literature to explain this kind of events. The first is the sudden transfer of angular momentum from the superfluid (or part of it) to the solid crust of the star. The second is a "starquake", a sudden breaking of the solid crust due to stress accumulated by the spin-down of the star. Our object of study is the second of these mechanisms, which was previously studied by Baym & Pines (1969). They showed that, for known values of Crab pulsar, starquakes due to spin down cannot explain the relatively short recurrence times (of few years), instead requiring hundreds of years between glitches. For Vela the scenario was much worse, exceeding thousands (even millions) of years the time between glitches. However, the size distribution of glitches is bimodal, so one might still try to explain the smaller glitches through this mechanism. In this investigation, using theory of elasticity to demonstrate how the star is deformed by rotation, we study the plausibility of the model in two scenarios. First in a completely solid star, which could store the maximum stress and the second is a more realistic star with fluid core and solid crust. We use observations of pulsars with only small glitches, as the Crab pulsar, and pulsars with bimodal distribution, as the Vela, to test the models.

Maria Argudo-Fernandez Universidad de Antofagasta

Evolution of Spiral Isolated Galaxies with MaNGA

From models, it is predicted that disks grow from inner to outer parts of galaxies, the so–called inside– out model of galaxy formation. As a consequence, we expect to observe gradients in stellar age and metallicity as a function of galactic radius. Thankfully, new integral field spectroscopy of nearby galaxies now provide us with data at sufficient resolution to study the star formation history (SFH) over the disk of a galaxy. But separating the effect secular evolution on the physical properties of galaxies from that of the environment (nature versus nurture) is also a necessary and challenging question to address. Here we report our efforts to constraint the SFH of isolated galaxies that have been already observed by MaNGA. Our preliminary results are in favour of the scenario where spiral disks grow inside-out. 9

Francisco Aros Pontificia Universidad Católica

Axisymmetric dynamical models of dwarf spheroidal galaxies

The dynamical analysis of dark matter dominated galaxies is expected to contribute significantly in the understanding of the nature of dark matter. In this sense, the local dwarf spheroidal galaxies are the perfect places for this kind of studies. Up to now most approaches have assumed spherical symmetry in both the data and the models, however we know that these galaxies are not spherical and we might have been biasing their masses. Here we present an axisymmetric approach via Jeans equations to model their velocity dispersion profiles with the goal of better constraining their halo mass distribution. We also analyze the relation of the velocity dispersion anisotropy in the meridional plane with the shape of the dark matter halo. Finally, we evaluate the validity of widely used (spherical) formulae for the mass within the half-light radius when axisymmetry is taken into account.

Roberto Assef Universidad Diego Portales

Hot Dust Obscured Galaxies

The WISE mission has discovered a rare population of high-redshift, hyper-luminous infrared galaxies, all with bolometric luminosities above log L_Bol/L_Sun > 13 , and many with log L_Bol/L_Sun > 14. Selected by their extremely red mid-IR colors and shown to have very hot dust temperatures, these hot, dust-obscured galaxies, or Hot DOGs for short, may probe a key stage in galaxy evolution. I will present the latest results of our ongoing research to understand the nature of these enigmatic objects from the point of view of our extensive X-ray through mid-IR photometric and optical spectroscopic follow-up observational campaigns.

Franz Bauer Pontificia Universidad Católica

A new type of X-ray transient

Our collaboration recently detected an X-ray transient in the Chandra Deep Field South, characterized by a sharp rise and decline at t^(-1.5), and a spectrum with Gamma=1.5+/-0.3. Subsequent follow-up to extremely deep limits with 8m telescopes and HST failed to detect any associated optical/near- infrared emission, ruling out many of the most likely known phenomena. We speculate on what options remain for explaining the event and possibilities for detecting similar events in the future. 12

Franz Bauer Pontificia Universidad Católica

Proposing for ALMA Cycle 4 and beyond in Chile

I will outline the rules that the ALMA Chilean Review Committee (CRC, http://www.das.uchile.cl/das_alma_crc.html) will implement to evaluate Chilean-based proposals in ALMA's upcoming Cycle 4 observation window, as well as provide some motivations for their implementation. Community feedback would be appreciated and could help the CRC to further clarify and streamline the process. The CRC and CHANCO (the CHilean ALMA National advisory COmmittee) would also like to gauge interest from the community regarding large programs (either implemented within the international TAC structure or outside of it) and what fraction of Chilean time might be reasonably devoted to such projects.

JUAN CARLOS BEAMIN Universidad de Valparaiso

Ultra cool dwarfs, revealing our neighbors

The last years several ultracool dwarfs have been found in our solar neighborhood. Discovering and characterizing these sources is key to really understand the physics of such cool objects, and are also important to study their abundance, multiplicity and distribution in our neighborhood. We started a campaign to characterize some of these new neighbors using spectroscopy, multiwavelength and multiepoch photometry, astrometry, and predicting possible future microlensing events with background sources. I will describe our main results the current status of the project and the future plans of this search and follow up campaign

Guillermo Blanc Universidad de Chile

Protecting the Dark Skies of Chile

Médéric Boquien Universidad de Antofagasta

Towards universal hybrid star formation rate estimators

Understanding when, where, and how stars form across the universe is a key question to understand the formation and the evolution of galaxies. Because if is easily accessible from the ground, the ultraviolet (UV) emission of massive, short-lived massive stars have been the star formation tracer of choice for distant galaxies. The launch of GALEX also opened this window for nearby galaxies, yielding unprecedented insight into star formation. Unfortunately the UV is efficiently absorbed by dust. At z~1.35, up to 90% of the emission of UV-emitting stars is absorbed by dust. Correcting for the presence of dust is therefore essential to trace star formation across cosmic times. To do so, one method that has become especially popular over the past decade is to combine the UV with mid- or far-infrared (IR) observations that trace the emission of the dust, the so-called hybrid star formation rate estimators. However different studies have led to different estimators, raising doubts about the actual accuracy of this method. In this talk I will present a state-of-the-art, spatially-resolved modelling of the spectral energy distributions of eight nearby galaxies that yield unprecedented insight into the origin of these differences. A detailed analysis shows that they are tightly linked to the star formation history of galaxies. I will show that it is possible to derive new, nearly universal hybrid star formation rate estimators, which do not suffer from the bias affecting popular hybrid estimators.

Johannes Buchner Pontificia Universidad Católica

The role of nuclear gas and host galaxy gas for obscuring GRB and AGN

Gas has a dual role in the Universe: it creates light e.g. by fusion in stars and accretion onto compact objects, but it also absorbs and extincts light. The most dense gas in the universe is probed by bright X-ray point sources, which includes exploding stars in the form of Gamma Ray Bursts and accreting black holes (AGN). Both frequently show extreme levels of gas column densities of ~10^22/cm² (GRB) and 10^24/cm² (AGN). An open research question is how such thick obscurers with large covering fractions are created and maintained. On the way to answering this question, my research clarifies the role of galaxy-scale obscuration, through (1) X-ray tomography reconstruction of host galaxy gas using GRB line-of-sight column densities and (2) by analysing modern hydrodynamic cosmological simulations which give predictions for the gas content of galaxies. With the host galaxy obscuration understood, observations provide useful constraints for models of AGN and GRB obscurers on the covering fraction at various levels of absorption.

Ricardo Bustos Universidad Católica de la Santísima Concepción

A new site for low frequency astronomy in Chile

The Medidor Autónomo de Radio Interferencia (MARI) was built at U. Católica de la Santísima Concepción (UCSC) to measure the Radio Frequency Interference (RFI) levels at isolated locations. A low-frequency telescope could be installed at a site with extremely low RFI levels for the detection of the faint 21-cm neutral Hydrogen line emitted during the Epoch of Re-ionization (EoR).

MARI-UCSC measured the RFI levels on the Paranal, Llullaillaco, and Chajnantor areas in the 50-200 MHz range. At these frequencies, FM radios, TV channels, satellites, and VHF transmitters are the main RFI contributors. In all of these areas significant RFI was detected. However, to the east side of the Chilean Andes, sites with extremely low RFI levels were found. In this talk, results from 7 measurement campaigns between 2014 and 2015 and an extension from 400 to 1500 MHz will be shown. These results open a new window of opportunities for low frequency astronomy in Chile. MARI-UCSC was supported by QUIMAL/CONICYT 2013. 18

Diego Calderón Pontificia Universidad Católica

Clump formation through colliding stellar winds in the Galactic Centre

The gas cloud G2 is currently being tidally disrupted by the Galactic Centre super-massive black hole, Sgr A*. The region around the black hole is populated by ~30 Wolf-Rayet stars, which produce strong outflows. Following an analytical approach, we explored the possibility that gas clumps, such as G2, originate from the collision of identical stellar winds via the Non-Linear Thin Shell Instability. We have found that the collision of relatively slow (< 750 km/s) and (strong 10^{-5} Msun/yr) stellar winds from stars at short separations (< 2000 AU) is a process that indeed could produce clumps of G2's mass and above.Such short separation encounters of single stars along their known orbits are not common in the Galactic Centre, however close binaries, such as IRS 16SW, are promising clump sources (see Calderón et al. 2016). Currently, we are modeling colliding wind systems in 2D using the hydrodynamics adaptive mesh refinement code RAMSES, aiming to obtain a clump mass function in order to understand how likely the formation of G2 is through this mechanism.

Abdo Campillay Universidad de La Serena

The massive O-type triple system Herschel 36 A

We performed a detailed high-resolution spectroscopic study of the extremely young massive multiple system Herschel 36 A. The study is, based on spectra collected in the "OWN Survey" (Barbá et al. 2010) high-resolution spectroscopic monitoring of southern Galactic O- and WN-type stars. Herschel 36 A is a hierarchical triple system composed by a 1.5 day period close binary (O9.5V+B0.5V) and a third massive component (O7.5 Vz) orbiting in a wider orbit, with 500 d period. We have applied a disentangling method on the spectra with the aim to separate the three stellar components with the disentangling method. We have calculated new spectroscopic orbits for the system based in the new radial velocities determined in the disentangling process. The separated spectra allow us to derive physical parameters for each star. The evolutive status of the system is briefly discussed

Graeme Candlish Universidad de Chile

Exploring alternatives to LCDM through simulations

While the LCDM cosmological model has proven remarkably successful, the two principle components, dark energy and dark matter, remain mysterious. There may also be indications of some tensions between this model and observations. Therefore it is worthwhile exploring alternative ideas. In this talk I will discuss the use of simulations to explore such alternatives, giving examples of numerical experiments that may allow us to test the predominant LCDM paradigm. 21

Paolo Cassata Universidad de Valparaiso

Lya haloes around normal star-forming galaxies at 2

Lyman alpha is the strongest line originating in star forming regions, and the Lya photons are redshifted in the optical at z>2. Therefore, Lyman alpha is routinely used to explore the high redshift Universe, up to and even beyond the epoch of reionization. However, the line is resonant, meaning that it is easily scattered/absorbed in the IGM of galaxies. As a result, “Lya escape fraction” (the fraction of the produced Lya photons that can eventually escape from the galaxy) is a complicated function of star formation activity, IGM and dust distribution, kinematics, ionization state and dust content. We used data from the Vimos-VLT Ultradeep Survey (VUDS) to investigate the presence of faint Lya haloes around normal star-forming galaxies at 2

Santi Cassisi INAF - Astronomical Observatory of Teramo

Multiple stellar populations in Galactic globular clusters: observational evidence and theoretical framework

During the last decade, one of the most important achievements in Stellar Astrophysics has been the discovery of the presence of multiple stellar populations in Galactic globular clusters. The presence of distinct sub-populations in these stellar systems is a challenge for the scenario of the cluster formation, but it has also a huge impact on many other research fields from the Galaxy formation to the "missing satellite problem". We plan to review the most recent observational evidence concerning the presence of distinct sub-populations in the same cluster, to discuss the many -- still-unresolved -- issues related to their formation, and the possible implication with Galaxy formation scenario.

Márcio Catelan Pontificia Universidad Católica

RR Lyrae stars in omega Centauri: Near-IR Properties and Period-Luminosity Relations

Luis Chavarria Universidad de Chile

How are we going to use the funds for the Chilean ARC?

I will present the current status and future opportunities to build a Chilean center for the ALMA data storage/analysis. 25

Nelvy Choque Universidad de Concepción

Using cosmological simulations to study groups in and around clusters

The role of the environment where a galaxy evolves, has received great importance during the last years. From previous studies we know now, that clusters have accreted a significant fraction of their final galaxy populations through galaxy groups. In this context, using high-resolution N-body cosmological simulations, we study the consequences of cluster and group environments for the evolution of galactic dark matter halos, trying to explain how the evolution of this halos proceed while within a host halo. Our results are focused about the mass loss of halos that belong to low mass groups, and discuss the role of certain parameters in determining this mass loss. Also we try to explain the main factors deciding whether a group-member halo "escapes" from its host group.

Sergio Contreras Pontificia Universidad Católica

How does the Halo Occupation Distribution evolve in time?

We use the Halo Occupation Distribution technique (HOD) to characterise the redshift evolution of different galaxy samples, using two independent models of galaxy formation. We measure the HOD for seven different number densities and for six redshifts between z=0 to z=3. We fit the HODs and show the evolution of their measured fit parameters. The parameters show a soft evolution in redshift, being able to represent them in a functional form for most cases. We also measure the ratio between M1 and Mmin, two of the fit parameters of the HOD that are normally used to characterise a galaxy sample (Guo et al. 2014). We compare the evolution of this ratio for different galaxy evolutionary models. The evolution of the fitting parameters show to be highly sensitive to the way galaxies evolve. We propose to use the HOD evolution to characterise galaxy samples of future galaxy surveys to improve our understanding of galaxy evolution and improve the quality of our galaxy formation models. We publish the functional form of the HOD so mock galaxy models can used them to populate galaxy samples in a wide redshift and number density range.

Juan Pablo Cordero Universidad de Chile

Searching for galaxy-galaxy interactions and merger relics in the Shapley Supercluster

We evaluate the merger activity of massive red sequence galaxies in the Shapley supercluster, using a spectroscopically complete sample of the 34 most massive cluster members, with high depth imaging obtained using DECam. The fraction of visually perturbed galaxies in the sample is the proxy employed for the estimation of the merger activity along with the inspection of possible companions revealed by close projection distance and line-of-sight velocity. We identify several highly perturbed systems, some of which can be regarded as a result of ongoing galaxy-galaxy interactions. Feature detection is carried out using GALFIT models and residual inspection. Detailed examination of the images of all red sequence galaxies in the sample reveals no apparent relation between the fraction of perturbed galaxies and clustocentric distance, contrary to the expected distribution assuming higher merger rates towards outer regions of clusters. 28

Johanna Coronado Pontificia Universidad Católica

Assembling the most distant sample of halo wide binaries from SDSS

Samples of wide binaries ($a\gtrsim$ 100 AU) are a gold mine for Galactic studies. They have been used on a large list of applications in a diversity of fields. In the dynamical arena, wide binaries provided the first meaningful constraints on the mass and nature of disk dark matter and, more recently, were used to close the remaining parameter space of MACHO-like halo dark matter not accessible to the micro-lensing campaigns. All these applications were possible when samples of these objects became large enough to not be dominated by random, chance alignments of two unrelated stars projected on the sky. Nevertheless, still today the largest available sample of the particularly valuable halo wide binaries \textit{free from selection biases}, contains not much more than 100 systems, and conclusions on dark matter are very sensitive to this fact. Here I propose to use proper motions from SDSS and data from Cerro Tololo, La Silla and Kitt Peak observatories to assemble a new sample of genuine halo wide binaries that will probe regions of the Galactic Halo not reached before with such dynamically sensitive test particles.

Marilyn Cruces Pontificia Universidad Católica

On the low magnetic fields of millisecond pulsars

Millisecond pulsars (MSPs) are old and very fast rotating neutron stars (NS) with much weaker magnetic fields than the younger classical pulsars and magnetars. Most MSPs are in binary systems, suggesting a "recycling scenario", in which a classical pulsar accretes matter from its companion and as a consequence spins up. Although this scenario explains the fast rotation, it is not clear yet how the magnetic field is reduced. The standard scenarios attribute it to the accretion process, either by increasing the temperature and thus the resistivity of the crust, leading to dissipation of the currents (assumed to flow in the crust), or by diamagnetic screening of the field by the accreted matter (which is implausible, because of magnetic buoyancy and the stiffness of the magnetic field lines). We examine an alternative scenario, where the magnetic field decay before the accretion through ambipolar diffusion. This mechanism is particularly effective during the long period in which the neutron star has cooled substantially and has not yet started accreting, making the final magnetic field dependent on the evolutionary time of the companion star (and thus its initial mass), and naturally yielding field strengths of the observed magnitudes.

Silvana Del Valle Bustos Universidad de Chile

Harassment - what is that? 31

Tanio Diaz-Santos Universidad Diego Portales

The Striking ISM of the Most Luminous Galaxy in the Universe

In this talk I will present results of spatially resolved ALMA [C II]157.7μm observations of W2246–0526, the most luminous galaxy in the Universe known. Located at z~4.6 and hosting a super-massive black hole in its center, we find a strikingly uniform, ~600 km/s wide line emission across the entire galaxy, a combination of properties not observed before in any other high redshift object. Such a large, homogeneous velocity dispersion indicates a highly turbulent interstellar medium (ISM). W2246–0526 is unstable in terms of the energy and momentum that are being injected into the ISM, strongly suggesting that the gas is being blown away from the system isotropically, likely reflecting a cathartic state on its road to becoming an un-obscured quasar. Caught at a time when the Universe was ramping up to its peak of star formation and SMBH accretion, our ALMA observations clearly reveal extreme conditions in the ISM of the most luminous galaxy known, where the feedback from the powerful active galactic nucleus is having a strong impact on the evolution and fate of the entire galaxy.

Raul Dominguez Universidad de Concepción

Effects of the Initial Mass Function and Mass Segregation in the Evolution of Embedded Star Cluters

Almost all stars are born in star clusters, and yet almost all stars are no longer part of them. A high number of young star clusters are observed in contrast to very few old ones. This absence of old clusters imply that some mechanisms are destroying the clusters in their youth,a phenomenon called Infant Mortality. The best candidate is the strong perturbation that is generated by the expulsion of the remaining gas from the newly formed star cluster. Numerical simulationsshow that the Star Formation Efficiency is a good parameter to estimate the survivability of a cluster to the expulsion of the gas. The surviving cluster is quantified with its final gravitationally bound mass through the final bound fraction . Simulations with initially clumpy and out of equilibrium distributions result in surviving clusters for SFE = 0.2 (Smith et al. (2012)). They introduce laterthe Local Stellar Fraction (LSF) and find new relations that helps to predict the survivability of star clusters. Farias et al. (2015) find a trend between the final bound fraction and the LSF when the virial ratio at the moment of gas expulsion is Qf = 0.5. All these studies weremade with equal-mass stars.In this project we explore how the introduction of an Initial Mass Function and Mass-Segregation affects the behaviour and results previously found for clusters with equal mass stars.

Holger Drass Pontificia Universidad Católica

Implementation of the metrology system for MOONS

The Multi-Object Optical and Near-infrared Spectrograph (MOONS) is a new fiber-fed spectrograph for the VLT. MOONS will exploit the full 500 square arcmin field of view offered by the Nasmyth focus of VLT and will be equipped with two dual-arm spectrographs covering the wavelength range 0.645 μm- 1.8 μm. Each double-arm spectrograph will produce spectra for 500 targets simultaneously. To ensure the accurate positioning of the 1000 fibers over the focal plane that has 880 mm in diameter, a metrology system has been designed to provide position measurements within ~10 μm. This talk presents the hardware and software design of the metrology system as accepted by the end of the preliminary design phase and subsequent improvements.

Sonia Duffau Millennium Institute of Astrophysics

Near-Field Cosmology with RR Lyrae Variable Stars: A first view of substructure in the Southern Sky

The arrival of the SDSS revealed that the northern-hemisphere halo has plenty of substructures (e.g., the Field of Streams; Belokurov et al. 2006). The southern-hemisphere sky, on the other hand, remains a "terra incognita" where only recently some substructure candidates have been found, thanks to ongoing wide-field surveys. Extending the census of halo overdensities to the southern sky is important as these structures provide clues into the Milky Way's merger history. Very recently, more than 20 southern overdensity candidates were found, using RR Lyrae data from the Catalina Real-time Transient Survey (Torrealba et al, 2015). However, the confirmation of those RR Lyrae overdensities as remnants of protogalactic fragments that may have helped build the present-day Galactic halo requires spectroscopic confirmation, in order to distinguish, using radial velocities and chemical information alike, bona-fide overdensities from random clumping among halo field stars. In this contribution, we will present preliminary results of a spectroscopic follow-up of several of the Torrealba et al. southern overdensity candidates, based on low-resolution spectra obtained with the SOAR and Magellan telescopes.

Cristobal Espinoza Pontificia Universidad Católica

The evolution of young pulsars

Pulsars are not seen to evolve according to the expectations of the available models. A proper characterisation of their long-term spin evolution, however, is possible only for the youngest sources. Even for them, this is a difficult job because the main trend is often obscured by short-term rotation irregularities, which respond to dynamical processes occurring inside and outside the star. A good understanding of these torques can thus lead to a better comprehension of megnetospheric physics and the extreme properties of matter inside neutron stars.Glitches are sudden, sporadic positive jumps in spin rate affecting the rotation of most pulsars. They are believed to be the response of the crust to an erratic interaction with an interior superfluid component that stays decoupled from the rest of the star's rotation. Here we present new long-term spin evolution measurements for glitching pulsars. We propose that the observed long-term trends, of these and other youngpulsars, could be explained by the standard models plus the progressivedecoupling of an internal superfluid component. 36

Carla Fuentes Universidad de Concepción

NuSTAR Serendipitous Survey: Results from Magellan

Since the first discovery of the Cosmic X-ray Background (CXB), astrophysics try to determine in detail its composition. One of the most important advances are from Chandra and XMM-Newton surveys, they already resolve just about 80% of the CXB < 8 keV. When we study at higher energies (E > 10 keV), only the 4% of the CXB are resolved. Now, thanks to NuSTAR, we can study X-ray sources at energies ∼ 20-30 keV peak and thus get a better understand of the growth of the supermassive black hole.NuSTAR it is observing known AGNs and find serendipitus sources arround them. So far it is detect more than 400 serendipitous sources, but only 44% has spectroscopic redshift. These sample is divided by those observed in the northern hemisphere and southern hemisphere. In this context, I will present the first 20 serendips from the Magellan Telescope, using MagE echelle spectrograph and IMACS spectrographs. We measured their redshifts, obtained their luminosities and study their obscuration.

Irma Fuentes Morales Universidad de Valparaiso

New data on old novae

The role of the nova eruption within the evolution of cataclysmic variables can be studied by comparing the population of post-nova systems with the general cataclysmic variables population.However the current sample of post-novae is not statistically signiﬁcant. In our project, we use photometry and spectroscopy in the optical to increase the sample of known post-novae. We here present a sample of our latest results.

Gazinur Galazutdinov Universidad Católica del Norte

C60+ - looking for the largest molecule in space

The recently published iby Cambell et al. (2015, Nature, 523, 322) gas phase spectra of molecule C60+ reactivate new attempts to confirm the presence of this molecule in the interstellar medium by means of analysis of spectra of hot reddened stars. The search for spectral features believed to be carried out by C60+ meet two issues have to be solved: (i) the wavelength range of interest is severely polluted by strong water vapor lines formed in the Earth atmosphere; (ii) the second strong 9633 Å interstellar feature attributed to C60+ is blended with strong stellar MgII line. For the first time we carefully considered both issues in the most representative up to now sample of lines of sight. We do not confirm the presence of C60+ in the interstellar medium. 39

Lluis Galbany Universidad de Chile

IFS of supernova host galaxies

The advent of Integral Field Spectroscopy (IFS) applied to supernova (SN) environmental studies have shown the potential of this technique to characterize the local environment, to measure directly the galactic environmental parameters at SN locations, and compare them to those at different locations of the galaxy. I will present the first statistical study using IFS of nearby SN host galaxies provided by the CALIFA survey, which consists of 132 SN of all types in 115 galaxies. We recovered the sequence in association of different SN types to the star-forming (SF) regions by using several indicators of the ongoing and recent SF related to both the ionized gas and the stellar populations. While the total ongoing SF is on average the same for the three SN types, SNIbc/IIb tend to occur closer to SF regions and in higher SF density locations than SNII and SNIa; the latter shows the weakest correlation. CCSN also tend to explode at positions with younger stellar populations than the galaxy average, but the galaxy properties at SNIa locations are one average the same as the global galaxy properties. When the AGN contribution is excluded from the total spectra, the average metallicity of the SNIa host galaxies is 0.03 dex higher the than the measured not excluding the AGN, which can be interpreted as a systematic effect when measuring metallicities of galaxies which structure cannot be resolved. We found a sequence from higher to lower metallicity, form SNIa to SNIc-BL, and significant increasing ratio of SNIc at higher metallicities compared to other CCSN types. Our results support that none of the two proposed SNIbc progenitors scenarios can be excluded, and the most probable situation is a combination of both. Finally, I will present the the on-going Chilean-based AMUSING survey that has already compiled a sample of more than 200 SN host galaxies using MUSE, the new IFS at VLT. AMUSING will be able for the first time to find direct correlations with such environmental parameters to the observed properties of the transients.

Stefano Garcia Pontificia Universidad Católica

Young galaxy candidates at z=7,8,9 and 10

We searched for z>7 Lyman-break galaxies in the optical-to-mid-infrared Hubble Frontier Field and associated parallel field observations of the strong-lensing cluster MACS J0416−2403. We discovered 22 candidates, of which 6 lie at z>9 and 1 lies at z>10. Based on the Hubble and Spitzer photometry, all have secure photometric redshifts and a negligible probability of being at lower redshifts. This substantial increase in the number of known high-redshift galaxies allows a solid determination of the luminosity function (LF) at z>8. One of the objects in the cluster field is a z ~ 10 candidate, with a magnification of μ∼ 20±13. This object is likely the faintest z ∼ 10 object known to date, allowing a first look into the extreme faint end (L∼ 0.04 L*) of the z ∼ 10 LF. We have named this galaxy “Tayna”, which means "first-born" in Aymara language. Tayna is proof of an underlying population of dimmer galaxies which may better represent high-z population than the brighter ones previously already reported. Since the researches point to that the reionization epoch span between z~10 and z~6, we may be observing the first representative galaxy emerging from the dark ages. 41

Felipe Garrido Goicovic Pontificia Universidad Católica

Orbital evolution of supermassive black hole binaries from infalling clouds

The formation of massive black hole binaries (MBHBs) is an unavoidable outcome of galaxy evolution via successive mergers. However, the mechanism that drives their orbital evolution from parsec separations down to the gravitational wave (GW) dominated regime is poorly understood and their final fate is still unclear.

If such binaries are embedded in gas-rich and turbulent environments, as observed in remnants of galaxy mergers, the interaction with gas clumps (or molecular clouds) may efficiently drive their orbital evolution. Using numerical simulations, we test this hypothesis by studying the dynamical evolution of an equal-mass and circular MBHBs accreting infalling molecular clouds. We investigate different orbital configurations, modelling a total of 13 systems to explore different possible pericentre distances and relative inclinations.

We show that the evolution of the binary orbital elements is dominated by the exchange of angular momentum with the accreted gas during the first stages of the interaction for every orbital configuration. Building on these results, we construct a simple model for evolving a MBHB interacting with a sequence of clouds drawn from reasonable populations with different levels of anisotropy. We show that the binary efficiently evolves down to the GW emission regime within few hundred million years, overcoming the 'final parsec problem'.

Doug Geisler Universidad de Concepción

CaTastrophe in the SMC

We present new results based on VLT Ca Triplet (CaT) medium resolution spectroscopy of some 200 red giantmembers of 29 SMC intermediate - old age clusters. We also derive accurate velocities and metallicities for about 750 surrounding field giants. Weinvestigate the metallicity distribution, age- metallicity relation and metallicity gradient in great detail for the SMCusing this large and homogeneous database. We find a number of interesting results and some surprising differencesbetween the clusters and field stars. We discuss these results and their implications for the formation and evolution of the SMC.

German Gomez Vargas Pontificia Universidad Católica

The Galactic Center excess in gamma rays

Many independent groups have claimed to find an unaccounted excess over conventional diffuse backgrounds in the data collected by the Fermi-LAT from the Galactic Center. The excess is compatible with dark matter predictions, nevertheless the modelling of gamma-ray sources in the line of sight of the Milky Way’s center is full of uncertainties. I will present results of a Fermi-LAT Collaboration analysis of the diffuse emission toward to the Galactic Center that give important insight on the excess nature. Different phenomena could account for the Galactic Center excess in gamma rays. Besides the dark matter interpretation, the other phenomena that may account for the excess are: a population of yet unresolved millisecond pulsars located in the bulge of the Milky Way, and secondary emission from cosmic-ray protons or electrons injected in the Galactic Center by past events. To distinguish between an unresolved population of point sources and an intrinsic diffuse emission as the real nature of the Galactic Center excess is challenging. I will present some statistical methods proposed to shed light on this issue, in particular the 1pt-PDF (number of pixels with k counts vs k counts) to characterize the clustering properties.

Roberto Gonzalez Pontificia Universidad Católica

Halo spin and filament connection at high redshift

We explore the spin evolution of dark matter halos and dependence on the number of connected filaments at high redshift(spin-filament relation). We found halos with fewer filaments have larger spin, We also found that this relation is more significant for higher halo masses, and for halos with quiet(no major mergers) assembly history. In addition halos with larger spin or with fewer filaments have their filaments more perpendicularly aligned with the spin vector.

Valentino Gonzalez Universidad de Chile

Galaxy Growth in the First 2 Billion years of the Universe.

As the Universe evolves, the structures in it grow in mass but at a rate that has been steadily decreasing since very early on. The first 2 billion years represent an epoch of very fast evolution and growth for galaxies. The study of this process in distant galaxies, however, requires extremely deep data that nowadays is only available thanks to the Hubble Space telescope and, very importantly, to Spitzer. Based on the deepest images from these two powerful telescopes today we can study the physical properties of these galaxies such as their ages, star formation rates, and stellar masses. By following the evolution of these properties in the early Universe, we are starting to understand the very first stages of galaxy evolution and the stellar mass growth in galaxies. In this talk I will review some of the most recent progress in this field (e.g., current estimates of the SFR density evolution, the galaxy stellar mass function, etc) and the current challenges that we face (e.g., the effect of strong emission lines in SED modeling, and their implications). I will also comment about a number of opportunities that the new facilities will open up for this exciting field in the near future, including prospects for JWST, ALMA, and the 30M class telescopes.

Alex Gormaz-Matamala Universidad de Valparaiso

New solutions to line driven winds of hot massive stars

Massive stars are important because they enrich the ISM with their powerful stellar winds.It is important to characterise accurately the winds of these stars (called line-driven winds) aiming to understand better how massive stars will evolve through their future stages, and how they contribute with the chemical enrichment of the galaxy.Many parameterisations have been done to line-driven winds under the m-CAK theory.However, they do not include self-consistent models taking in count hydrodynamics, and also neglect the effects of the ionisation density (fast solutions).In this talk, we present our first solutions to the line-force parameters (alfa, k, delta), found to line-driven winds in a self-consistent way under LTE conditions.Hydrodynamic models are provided by the code HydWind.We compare these results with those found by previous studies, focusing in what regions of the optical depth are used to do the calculations.We also evaluate how far change the solutions when the effects of ionisation density are taken into count (delta-slow solutions).And finally, we also present our first approaches to calculate alfa. k and delta to non-LTE environments.

Mariusz Gromadzki Universidad de Valparaiso

Searching for the coolest brown dwarfs in the Galaxy

We have explored the WISE All-Sky database applying various selection criteria to obtain sample of W2-only detected and low signal-to-noise (S/N≥ 8) late T and Y dwarf candidates. Spurious sources were removed using database selection criteria defined through analysis of a control sample comprising isolated point-like non-variable non-moving sources from the SDSS. We perform J-band photometric follow-up on 4- to 8-m class telescopes to prove the high proper motion and low temperature of these objects. The low resolution near-IR spectroscopy of the best candidates has confirmed nine late T dwarfs (>T8) and one Y dwarf. Here we will present a summary of ground based photometric and spectroscopic follow-up of the candidates.

Claudia Gutiérrez Universidad de Chile

Spectral diversity of type II Supervoae

We present a spectroscopic analysis of type II Supernovae (SNe) obtained by the Carnegie Supernova Project (CSP) plus previous campaigns between 1986 and 2009. A total of 127 SNe with ~900 spectra were analyzed. Spectral information such as the appearance of the lines, pseudo- equivalent widths (pEWs) and velocities are analyzed and correlated with photometric parameters. We find that in faster declining SNe II spectral lines appear at later epochs than slow declining SNe. In addition, slow declining SNe (IIP) have higher pEWs values and lower velocities.

Gergely Hajdu Pontificia Universidad Católica

RR Lyrae stars in binary systems

RR Lyrae stars are fundamental stellar probes of astrophysics: theireasily identifiable, characteristic light curves, together withtheir well-known magnitudes, makes them excellent distance indicators.Furthermore, the properties of their pulsation (period, light-curveamplitude and shape) are strongly dependent on the stellar interior,thus providing important constraints on the theory of the structureand evolution of old, low-mass stars. However, the theories of stellarpulsation and evolution both lack a crucial constraint: no direct massmeasurements for any RR Lyrae star has ever been reported. Indeed, upto this point, only one RR Lyrae variable has been known to reside ina binary system, despite the discovery of over 100,000 stars of thisclass.I describe our search for RR Lyrae stars in binary systems throughthe light-travel time effect, utilizing the decade-long OGLE survey light curves towards the Galactic bulge. We have found and published20 candidates in our initial search.In this talk I describe the sample and methods utilized for our search,as well as the prospects for finally achieving a direct massdetermination of RR Lyrae stars through the follow up of our binaries.

Sebastian Hidalgo Instituto de Astrofísica de Canarias

Radial gradients in dwarf galaxies from resolved stellar populations

I present results of deriving the star formation history as a function of radiusfor a set of dwarf galaxies of the Local Group. The results show a radial gradient in ages and metallicities of the stars in which younger and less metal poor stars tends to be more concentrated towards the center of the galaxies. As a result, the scale length of the galaxy evolves with time. A detailed analysis of the radial gradients may shed light on the of early effects of physical process, like the UV-background or SNe feedback, in the evolution of dwarf galaxies.

Thomas Hughes Universidad de Valparaiso

Tracing star formation with spatially-resolved [NII] 205 line emission in nearby galaxies

The recent success of Herschel is enabling the detailed study of star formation and the physical conditions in the interstellar medium via observations of the far-infrared fine-structure lines. Spatially- resolved observations of nearby galaxies will be crucial for understanding the physical conditions in distant galaxies observable with ALMA. We investigate the spatially-resolved correlations between the [NII] 205 um line emission, the 24 um continuum, and the local star formation rate seen in five members of the Very Nearby Galaxies Survey. We find strong correlations between all three quantities, although both the nuclear starburst in M83 and the merger-induced star formation in the Antennae galaxies exhibit less [NII] emission per unit SFR surface density than the normal star-forming discs of M51 and NGC 891. Regions of intense star formation typically yield stronger ionization parameters, which suggests that either other higher ionization lines become more important for gas cooling, or dust obscuration could be more effective at reducing gas heating in more compact HII regions.

Eduardo Ibar Universidad de Valparaiso

The molecular gas and dust content in `normal' star-forming galaxies at z = 1.46 & 2.23 observed with ALMA

We show ALMA observations to `normal' H-alpha star-forming galaxies at z=1.46 and 2.23 selected from the High-z Emission Line Survey (HiZELS). Their H-alpha emission was previously observed with SINFONI at ~0.2" (~1kpc) resolution revealing thick rotating disks presenting massive clumps of star- formation. Using ALMA Band-3 we observe at ~3" resolution unusually large and massive reservoirs of cold molecular gas in complex dynamics with respect to that seen in H-alpha. The molecular gas mass are usually ~2-3 times larger than the mass seen in stars (f_gas~0.4-0.7) and significantly extended (up to ~20kpc) compared to the size revealed by SINFONI, or compared to colour-selected passive galaxies at similar redshifts. Even though HiZELS have dramatic differences in terms of gas content, their integrated properties follow the Kennicutt-Schmidt law, similarly to `normal' galaxies seen in the local Universe. Considering the H-alpha-derived dust-corrected star-formation rates they fall in the so-called `long-lasting' mode of star-formation (up to tau_gas=8Gyr) which could continue up to the present day at their observed SFRs. We do not detect any rest-frame 350um continuum emission down to ~25uJy/beam (at ~0.3" resolution), possibly due to higher dust temperatures or lower level of clumpiness in dust-emission compared to that seen in H-alpha.

Daniela Iglesias Universidad de Valparaiso

Where gas was not expected

A debris disk is commonly described as a second generation circumstellar disk composed of dust grains, planetesimals (asteroids and comets) and possibly already formed giant planets. Such bodies would be the remnants of the planetary formation process that took place around the star. It was long thought that debris disks were systems fully depleted of gas, but in the last few years the presence of gas has been detected in a handful of them. The nature of this gas is still under debate; it may be residual gas (leftover from earlier stages of the disk) or second generation gas (generated by falling evaporating bodies), however, both possibilities would have great implications in the process of planet formation and evolution. An efficient way to detect this gas in debris disks is monitoring gas tracers using multi-epoch high-resolution spectroscopy (e.g. Kiefer et al. 2014). In the course of my thesis, I am investigating the presence of gas in a sample of ~300 well constrained debris disk (Olofsson et al. in prep) in order to establish the frequency and main properties of their gaseous content. The final goal is to determine the origin of these gaseous components, and look for correlations with the age and dust properties of the disks. As a byproduct of this ongoing large project, in this talk I will be presenting a particularly interesting object that exhibits two different stable circumstellar gas features. I will discuss the possible origin of this gas based on its properties, and put this component in the context of the dust properties / distribution.

Yara Jaffé European Southern Observatory

The fate of HI gas and the quenching of galaxies in evolving environments

In a hierarchical Universe clusters grow via the accretion of galaxies from the field, groups and even other clusters. As this happens, galaxies can loose and/or consume their gas reservoirs via different mechanisms, eventually quenching their star-formation. I will present recent results from BUDHIES (a deep HI survey) and GASP (a MUSE large program) on the impact of ram-pressure stripping of HI gas and star formation in cluster galaxies. In particular, I will show extreme cases of striping, know to be responsible for "jellyfish" morphology. Finally I will discuss the role of group pre- and post-processing in the quenching of galaxies. 55

James Jenkins Universidad de Chile

New Planetary Systems from the Calan-Hertfordshire Extrasolar Planet Search and Core Accretion Mass Limit

I will discuss the discovery of eight new giant planets and updated orbits for four previously detected planets from the Calan-Hertfordshire Extrasolar Planet Search. The planets have masses in the range 1.1-5.4Mj's, orbital periods from 40-2900 days, and eccentricities from 0.0-0.6. They include a double- planet system orbiting the most massive star in our sample, two eccentric giant planets, and a rare 14 Herculis analogue. I will discuss a possible over abundance of Jupiter-mass objects compared to a simple power law fit to the mass function for all currently known planets detected by the radial velocity method, with a steep increase in the planet frequency around 3Mj, reflecting the increased efficiency of planet formation towards lower masses. This truncation of the mass function could provide the sought after upper limit of planetary-masses that can be formed by gas accretion onto a forming proto-planet, constraining future hydrodynamical models. I will also show that low-mass planets tend to be found orbiting more metal-poor stars than giant planets, yet the functional form of the mass distribution does not change with metallicity. Finally I will show that giant planets with periods less than 100 days orbit stars that are significantly more metal-rich than those on longer period orbits, a so-called period- metallicity correlation, and I will discuss what this means for theoretical models.

Matias Jones Pontificia Universidad Católica

6 years of the EXPRESS radial velocity survey

In this talk I will present the results of the EXPRESS (EXoPlanets aRound Evolved StarS) survey, after 6 years of observations.

Stefan Kimeswenger Universidad Católica del Norte

Planetary Nebula - modelling vs. observations

Planetary nebulae (PNe) are a very special laboratory in space. Just like other ionized nebulae, the physics has been extensively studied. As long as the equilibrium is valid, the theory is considered largely understood. Although the standard model of the colliding two wind system (Kwok, 2007, The Origin and Evolution of Planetary Nebulae, Cambridge) is still the basis of our understanding, deeper insights show, that it can`t be that simple. The optical thickness near unity, positioning them between stellar atmosphere and the interstellar matter, makes modeling and interpretation of observations difficult. Here we intend to proceed towards a more general model of the PNe evolution. The numerical magneto hydrodynamic code CRONOS was recently adopted to PNe and is combined for the radiation part with CLOUDY. This allows unique access for adapting the code down to the solver level. This is combined with observational data for giving better boundary conditions. 58

Valery Kravtsov Universidad de Atacama

Chemical evolution of galaxies and the formation of massive star clusters

Starburst events in dwarf galaxies, with stellar mass ~10^9 – 10^10 Msolar and with typical metallicity [O/H] > -1.0, are known to be responsible for the formations of young/intermediate-age massive star clusters (YIMSCs), with typical masses falling in the range of the globular cluster (GC) mass. These events and the formation of the YIMSCs are widely believed to be an accidental process fully dependent on and driven by external factors, such as merging or strong interactions. However, nearly ten years ago, analyzing a variety of data available and published to date, we argued, for the first time, that the formation of both the YIMSC populations in dwarf (irregular) galaxies and the populations of metal-rich GCs in spheroids occurs at approximately the same stage of the host galaxies' chemical evolution. It is related to the essentially increased star formation (SF) activity in the hosts around the same metallicity , ~1/3 of the solar one. It is achieved very early in massive spheroids, later in lower mass spheroids, and much later in irregular galaxies. In the present contribution we demonstrate one more piece of supporting evidence of essentially increased SF activity in dwarf galaxies around this particular metallicity. This observing evidence is based on published direct estimates of both relative SF rate and metallicity (oxygen abundance) in a very large sample of star-forming galaxies in the nearby Universe, at very low redshift.

Michael Kuhn Universidad de Valparaiso

Mass Segregation in Star-Forming Regions

Mass segregation of stellar populations—in which more massive stars are more strongly clustered than lower mass stars—is often observed in star-forming regions. We investigate the spatial distribution of stars in 17 of the nearest sites of high-mass star-formation in the Galaxy, using the MYStIX sample of X-ray selected and infrared selected cluster members. We find that in some regions, not only the O-type stars are segregated, but also low-mass stars down to 1.5 solar masses (a result not expected from simulations of dynamically induced mass segregation). Although mass segregation is clearly present in some cases, other regions have no mass segregation, and others have the segregation reversed. There is no evidence for increasing segregation with cluster age (as would be expected from dynamical simulations), but there is indication that the densest clusters tend to have their most massive star located at their centers. Our results of mass segregation at low- masses and mass segregation independent of cluster age support the conclusion that the process of star-formation, either through competitive accretion or mass-segregated pre-stellar cores, yields primordially segregated clusters.

Ivan Lacerna Pontificia Universidad Católica

Isolated elliptical galaxies

I will present a sample of 89 nearby isolated elliptical galaxies, whose physical properties are compared with elliptical galaxies located in a high-density environment such as the Coma supercluster. The aim is to probe the role of environment on the morphological transformation and quenching of elliptical galaxies as a function of mass. In addition, I will discuss about the nature of a particular set of blue and star-forming isolated ellipticals identified here. They are young galaxies with light-weighted stellar ages <= 1 Gyr and exhibit bluer colors toward the galaxy center. I will show that the processes of morphological transformation and quenching seem to be in general independent of environment since most of elliptical galaxies are "red and dead", although the transition to the red sequence should be faster for isolated ellipticals. In some cases, the isolated environment seems to propitiate the rejuvenation of ellipticals by recent (< 1 Gyr) cold gas accretion.

Nancy Levenson Gemini Observatory

New Opportunities at Gemini Observatory

I will discuss some of the exciting opportunities now available at Gemini Observatory. We have introduced new modes of applying for observing time, including the Fast Turnaround and Large and Long Programs, in addition to the usual semester allocations. We have several new opportunities for community members to become involved with instrumentation, including small and medium projects that external instrument teams carry out. Visitor instruments are open to all for science use, and new facility instruments will arrive over the next few years.

Paul Leyton Pontificia Universidad Católica

Reddening-free indices for the VISTA filter system

Extinction levels can be very significant, particularly towards the inner and very obscured regions of the Milky Way. Reddening-free indices are suitable, linear combinations of colors and magnitudes, so that the resulting "pseudo-magnitudes" and "pseudo-colors" are, by construction, insensitive to reddening. Multiple indices have been defined by us, using different filter combinations from the VISTA filter system (ZYJHKs). We have analyzed the dependence of these indices on extinction law and spectral types, and here we report on the performance of the different indices, by applying them to data obtained in the framework of the VVV ESO Public Survey.

Carlos Hugo López Caraballo Universidad de La Serena

CPD-26 2716: a new runaway O-type supergiant star characterized from the GOSSS and OWN optical spectroscopic surveys

This work is result of the synergy of two spectroscopic survey that are being carry out from Chile, Argentina and Spain. The "Galactic O-Star Spectroscopic Survey" (GOSSS) is a large program that is currently obtaining intermediate resolution optical spectra of all O-type stars brighter than B=14 in the Milky Way. The "High-resolution spectroscopic monitoring of Galactic O and WN-type stars" (OWN Survey) is a extensive spectroscopic monitoring of 240 southern stars with the aim to monitor radial velocity and spectral variations. Here, we used the OWN and GOSSS data in order to characterize the properties, and the runaway nature, of the O-type supergiant star CPD-26 2716 (LS840). The picture is reinforce with the presence of a bow-shock structure in the mid-infrared images. Although the uncertainties are considerable the reconstructed trajectory allows us to identify the candidate cluster (Ru 44) that originally hosted this runaway. The HRD of Ru 44 is constructed using stars with known spectral type (from literature), and the LS840 is candidate to be a blue straggler star.

Francesco Mauro Universidad de Concepción

Photometric studying the Horizontal Branch of NGC6440 and NGC6569 with GeMS/GSAOI

NGC6440 and NGC6569, two massive and metal-rich bulge Galactic globular clusters (BGGCs), were shown to present features in the Horizontal Branch (HB, Mauro et al. 2012). Here we present the results from the near-infrared (NIR) photometric follow-up using the GeMS-GSAOI. This NIR camera at Gemini South Observatory, thanks to its state-of-the-art adaptive optic system, permits to analyze really crowded field. We merged this new NIR photometry of the central part of the two BGGCs with the previous NIR photometry from "Vista Variables in the Via Lactea" ESO Survey to study the characteristics of HBs in the full range of radial distance.

Alejandra Melo Universidad de Concepción

Physical Properties of Hard X-ray Emitters in the NuSTAR Serendipitous Survey

One of the key goals of high-energy astrophysics is to determine the detailed composition of the cosmic X-ray background (CXB) at its ∼ 20-30 keV peak. This is critical in order to understand the growth of the supermassive black holes that can be found at the center of each (massive) galaxy. A major breakthrough in our studies of the CXB is NuSTAR, the first focusing X-ray observatory with high sensitivity at E>10 keV. We obtained multi- band optical to near-IR spectral energy distributions (SEDs) for the hard X-ray emitters detected as part of the NuSTAR serendipitous survey. Combined with existing GALEX, Spitzer and WISE UV and near/mid-IR photometry, constructed multi-wavelength SEDs for these sources, which account for ∼ 35% of the CXB at its peak. This information will allow us to separate the emission from the Active Galactic Nucleus (AGN) and the host galaxy, and study the physical properties of the stellar populations such as age, metallicity and stellar mass. This is a critical ingredient in our understanding of the AGN/Galaxy co-evolution.

Ronald Mennickent Universidad de Concepción

Recent results of the investigation of interacting binaries and Be stars

We present recent results of the investigation of interacting binaries and Be stars. A comparison between the classes W Serpentids and Double Periodic Variables is made, obtaining interesting insights on the nature of these systems. In addition, some peculiar Be stars with photometric periods and recurrent eruptions are presented. We present results based on CHIRON high-resolution spectroscopy and OGLE & ASAS photometric time series. We also include examples of light curves models of binary stars with circumstellar discs. 67

Steffen Mietzke European Southern Observatory

European Southern Observatory

Dante Minniti Universidad Nacional Andrés Bello

The future of the VVV survey

Juan Molina Universidad de Chile

SINFONI-HiZELS, tracing the fomation and evolution of star-forming galaxies across cosmic time

The majority of the stars in the most massive galaxies (M_star > 10¹¹ M_sol) formed around 9-10 billion years ago, an epoch when star formation was at its peak. Galaxies at this epoch are very different from their counterparts in the local universe, they appear to be more gas rich (f_gas = 20- 80%) turbulent clumpy disks (M_clump ~ 10⁸⁻⁹ M_sol), with high velocity dispersions given their rotational velocities (sigma = 30-100 km s⁻ ¹; v/sigma ~ 0.2 - 1). In order to refine or refuse current models of this galaxies the observational challenge is now to quantitatively measure their internal properties.I'll present AO-assisted integral field spectroscopy (~0.15" -> ~kpc-scale @ z1-3) of Halpha- selected star-forming 'normal galaxies' at z = 0.84-2.23 drawn from HiZELS narrowband survey. This observations map the kinematics of these star-forming galaxies on ~kpc scales.

Maximiliano Moyano Universidad Católica del Norte

Broadband transmission Spectra of Hot Jupiters

In this talk I will review ongoing work on the characterization of Hot Jupiters using multiwavelength observations. I will present the results and outline the future work on this exciting field. 71

Alejandra Muñoz Arancibia Universidad de Valparaiso

Modeling complex emission processes in galaxy populations through the Proxy+Matching technique

We introduce a novel technique for modeling luminosities at different wavelengths in large samples of galaxies, suitable for emission processes whose complexity requires many untested assumptions or the use of sophisticated algorithms: in the "Proxy+Matching" approach, a physical galaxy property from the model is chosen as a proxy for another property whose numerical value is unknown. Both proxy and unknown are assumed to follow a monotonic relationship, assigning that unknown to the simulated galaxies in such a way that some observational statistics for it are reproduced. By comparing the predictions for further galaxy properties with observations, a good proxy can be found.We present the prospects of this technique for probing the submillimeter and Lyman alpha emission from galaxies in a cosmological framework, using a semi-analytic model of galaxy formation and evolution. 72

Julie Nantais Universidad Nacional Andrés Bello

The Urbanization of the Cosmos at z > 1.3

Mature galaxy clusters abound at z <= 1, with galaxy populations very different from the field. Although a few mature clusters are found at z ~ 1.5, it is unclear whether they are representative of dense environment evolution in their epoch. We explore the state of galaxy evolution in a sample of four of the richest z > 1.3 protoclusters and filaments from the SpARCS survey, focusing on their stellar mass functions and passive fractions as compared to the field at similar redshift and mature SpARCS galaxy clusters at lower redshift. Their stellar mass functions are similar to those of field galaxies, with only marginally more low-mass passive galaxies. The environmental quenching efficiency is ~11 +/- 3%, much lower than for z ~ 1 galaxy clusters. This implies that environmental effects may turn on later for typical dense systems, or else that these and many other dense systems found in near-IR surveys may not in fact be galaxy cluster progenitors.

Keiichi Ohnaka Universidad Católica del Norte

Milliarcsecond near-IR aperture-synthesis imaging of the red giant L2 Puppis with VLTI/AMBER and VLT/NACO

The red giant L2 Pup started a dimming event in 1994, which is considered to be caused by the ejection of dust clouds. We present near-IR aperture-synthesis imaging of L2 Pup with a spatial resolution of 6 milliarcsecond achieved by combining data from VLT/NACO and the AMBER instrument of the Very Large Telescope Interferometer (VLTI). The image obtained at 2.27 micron shows a nearly edge-on disk with a size of ~180 x 50 mas. Furthermore, thanks to the high spatial resolution of VLTI/AMBER, we see that the southern hemisphere of the central star is severely obscured by the equatorial dust lane of the disk. The angular size of the disk is consistent with the distance that the dust clouds that were ejected at the onset of the dimming event should have traveled by the time of our observations, if we assume that the dust clouds moved radially. This implies that the formation of the disk may be responsible for the dimming event. 74

Felipe Olivares E. Universidad Nacional Andrés Bello

The nature of type IIb supernovae

Core-collapse supernovae (SNe) are the final fate of massive stars, which explode with a variety of configurations. Type IIb SNe correspond to those with progenitors that are able to retain a small fraction of their H envelope. Therefore their spectra is dominated by H at early stages and by He later on. These type of SNe are usually fainter and less energetic than their type Ibc cousins, which are thought to have more massive progenitors. However, on March 9, 2013, the type IIb SN 2013ak is discovered by CHASE in the galaxy ESO 430-20. Quite luminous and with high expansion velocities, SN 2013ak offers a link between type IIb SNe and the more energetic broad-lined type Ic, whose progenitors have lost their H and He envelopes before explosion. Similar properties are shown by the recent type IIb SN 2015ap. Here we present a comprehensive analysis of the photometry and spectroscopy of both SN 2013ak and SN 2015ap.

Grecco Oyarzun Universidad de Chile

HOW LYMAN ALPHA EMISSION DEPENDS ON STELLAR MASS

In this work, we show how the stellar mass (M∗ ) of galaxies affects the 3 < z < 4.6 Lyα EW distribution. To this end, we design a sample of 629 galaxies in the M∗ range 7.6 < log M ∗ /M ⊙ < 10.6 from the 3DHST/CANDELS survey (Koekemoer et al. 2011). We perform spectroscopic observations of this sample using the Michigan/Magellan Fiber System (M2FS), allowing us to measure Lyα fluxes and use 3DHST/CANDELS ancillary data. In order to study the Lyα EW distribution dependence on M∗ , we split the whole sample in 3 stellar mass bins. We find that, in all bins, the distribution is best represented by an exponential profile of the form dN(M∗ )/dEW = W0(M ∗ )−1A(M ∗ )e−EW/W0(M ∗ ). Through a Bayesian analysis, we confirm that lower M∗ galaxies have higher Lyα EWs. We also find that the fraction A of galaxies featuring emission and the e-folding scale W0 of the distribution anti- correlate with M∗ , recovering expressions of the form A(M ∗ ) = −0.26(.13) log M ∗ /M ⊙ + 3.02(3.4) and W0(M∗ ) = −15.7(1.2) log M ∗ /M ⊙ + 167(33). These results are crucial for proper interpretation of Lyα emission trends reported in the literature that may be affected by strong M∗ selection biases.

Blake Pantoja Universidad de Chile

A SPHERE Discovery of an M-Dwarf Companion to HD 86006

Radial velocities have long proved to be a powerful method of detecting low-mass companions to stars, but they come with the inherent limitation that only minimum masses can be constrained by them due to their unknown limitations. With direct imaging, on the other hand, allows us to constrain their inclination, and used together, allows us to probe into the mass/period parameter space of the targets. We present here a detection of an M-dwarf companion to HD 86006 using SPHERE during Science Verification, 4.5 mag fainter than the primary at a 25 AU distance, along with some preliminary results from our run with the Magellan Adaptive Optics instrument. By searching for targets with long- period radial velocity trends, we were able to search for objects with a known but unseen companion. This discovery gives us the exciting opportunity to futher constrain the mass-luminosity relation for low- mass stars, allowing us to expand our understanding of the most types of stars and substellar objects.

Francisco Paz Chinchón Millennium Institute of Astrophysics

Rotational periods on Kepler planetary host stars: methods and results

We analyzed the host stars of a sample of confirmed planets detected by Kepler and Kepler Objects of Interest to compute new photometric rotation periods and to study the behavior of their angular momentum. Lomb– Scargle periodograms, wavelet transform maps, autocorrelation function, and correntropy generalized periodograms (Protopapas et al, 2015) were computed. The aim was focused on compare methods, performances and results as a way to test "recipes" for time domain astronomy. Our focus is to contribute to forthcoming LSST reduction techniques and data analysis.

Karla Peña Ramírez Pontificia Universidad Católica

From high mass stars to planetary mass objects.

The extension of the initial mass function towards the planetary mass regime and the search for the end of the mass function is extremely relevant to determine which is the dominant substellar formation process. I have been involved in the characterization of the lowest mass population (from ~13 down to 4-5 Jupiter masses) in three different star forming regions: the Sigma Orionis cluster (~3Myr, ~380 pc) the Upper Scorpius association (~5-11 Myr, ~145 pc), and the Rho Ophiuchi cloud (~1 Myr, ~145 pc). I will summarize some of our most important results as well as the limits that these kind of studies are facing. 79

Cristóbal Petrovich Canadian Institute for Theoretical Astrophysics

Unstable planetary systems and the origin of the hot and warm Jupiters

Various lines of evidence indicate that planetary systems often undergo orbital dynamical instabilities at different stages of their evolution. I will show how these dynamical instabilities can lead to the formation of the hot Jupiters (gas giant planets with orbital periods <10 days), whose origin remains a fundamental unresolved question in planet formation. Similarly, I will argue that this dynamical origin of the hot Jupiters can lead to the formation of a population of warm Jupiters (periods ~10-100 days), which are difficult to account for by other traditional mechanisms. I will compare the results from our model with the currently available data (spin-orbit angles, eccentricities, periods, etc…) and outline a set of predictions in preparation for the upcoming surveys (e.g., GAIA, TESS), which will help to test our theory. 80

Danae Polychroni Universidad de Atacama

Exploring the Importance of Location and Environment in Star Formation

The last few years have seen the advent of new technologies in the sub-mm and IR regimes that allow for unprecedented quality observations of star forming regions. As such we are finally able to produce statistically significant samples of star forming cores at the same time as mapping their surrounding environment with high spatial resolution. In this talk I will present results from the Herschel Space Observatory Gould Belt and HOBYs surveys that covered the Orion A Molecular Cloud complex and the W3 Giant Molecular Cloud as well as relevant results from ancillary observations. Both these regions contain intermediate to high mass star formation and a rich environment that includes triggered and spontaneous star forming regions as well as a plethora of filaments. We used this wealth of observations to obtain a statistically significant sample of star forming cores located in different environments and we have derived the properties both of the dense cores as well as their surrounding environment. As such, in this talk I will discuss the role of the environment in deciding the final mass of the forming stars with a focus in the presence of filaments and triggering phenomena in these two star forming regions.

Joaquin Prieto Universidad de Chile

Cosmological mass transport on galactic nuclei

By using AMR cosmological hydrodynamic N-body zoom-in simulations, with the RAMSES code, we studied the mass transport processes onto galactic nuclei from high redshift up to z~6. Due to the large dynamical range of the simulations we were able to study the mass accretion process on scales from ~50 kpc to ~pc. The SMBHs are modelled as a sink particles at the center of our galaxies, which allowed us to quantify the BH growth in relation with the mass transport processes associated to three different angular momentum fluxes: i) Reynolds stress, ii) gravitational stress and iii) viscous stress. Such a quantification allowed us to identify the main mass transport process as a function of the scales of the problem. Wefound that in simulations that include radiative cooling and SNe feedback, the SMBH grows at the Eddington limit most of the time. The disk momentum flux is dominated by the Reynolds stress transporting mass at a rate of ~1-10 Msun/yr. This level of SMBHs accretion rates found in our cosmological simulation, are needed in all models of SMBH growth attempted to explain the formation of redshift 6-7 quasars.

Jose Prieto Universidad Diego Portales

Tidal Disruption Events from ASAS-SN: characterization, host galaxies, and rates

The All-Sky Automated Survey for SuperNovae (ASAS-SN) is surveying all the sky for transients down to V~17 mag every ~2 days using 8x 14-cm telescopes in Haleakala and CTIO. Since the real-time transient survey started in May 2013, we have discovered three luminous nuclear outbursts (ASASSN- 14ae, ASASSN-14li, and ASASSN-15oi) that are consistent with the tidal disruption flares of stars by supermassive black-holes. In this talk, I will show the main observational characteristics of these events, their host galaxies, and their derived rates.

George Privon Universidad de Concepción

Dense Gas Tracers in the ULIRG IRAS 13120-5453

(Poster is acceptable if talk is not accepted). Molecular gas, probed by CO, has long been associated with ongoing star formation, but the total molecular gas mass is not linearly correlated with the total star formation rate in galaxies. In contrast, molecules such as HCN and HCO+, which trace higher density gas, show linear correlations with the star formation rate. This suggests HCN and HCO+ trace the dense gas intimately related to ongoing star formation. However, in active galactic nuclei and some starbursts, the HCN emission is enhanced (relative to star-forming galaxies), suggesting the HCN excitation may depend on radiative environment (X-rays, IR continuum). Thus, understanding the excitation of HCN and HCO+ is critical to understanding star formation in both star-forming galaxies and AGN. I will present ALMA observations of HCN and HCO+ in the AGN-hosting ULIRG IRAS 13120+5453 and discuss constraints on the excitation mechanisms for these dense gas tracers. I will conclude with a scenario for the overall properties of the ISM and its relation to the AGN and nuclear starburst.

Sebastián Ramírez Alegría Universidad de Valparaiso

VVV young clusters with a confirmed OB-population

Near and mid-infrared all-sky surveys such as 2MASS (Skrutskie et al. 2006), GLIMPSE (Benjamin et al. 2003), and UKIDSS (Lawrence et al. 2007) were key in the discovery of young and very obscured stellar clusters in our Galaxy. But the census is still far from complete; up to 3000 open clusters may still remain hidden in our Galaxy (Bonatto et al. 2006).

We present the latest clusters discovered using the ESO public survey Vista Variables in the Via Láctea (VVV; Minniti et al. 2010, Saito et al. 2012), particularly those with spectroscopically confirmed massive stellar population (Wolf-Rayet or OB-dwarfs). These objects are part of our long-term program dedicated to build a database of a great number of open clusters with homogeneously derived physical parameters.

Ricardo Ramírez Reyes Universidad de Chile

High Precision Spectro Astrometry in HD 100546

Spectro-Astrometry is a relative new thence that mesure the astrometry position respect to wavelength (Whelan and Garcia 2008). This method has been applied traditionally apply to long-slit spectroscopic observations (Takami et al. 2003), which has been used to discovering binary companions, studying the kinematics of YSO and narrow-line region of AGNs. But has been know to be affected by artefacts that may be misinterpreted as a real spectre-astrometric signal (Brannigan et al 2005).We apply this technique in the SINFONI instrument in K band in a brighter Herbig star HD100546, where we have reached a positional accuracy (rms) of 30 micro arcseconds (0.03 milli-arcseconds), corresponding to the size scale of the stellar radius. We discover an artefact that affects the signal in the perpendicular direction of the diffraction axis. We developed a method to remove them by the combination of the different observation with different PA of the same objects, using the telluric line as a test. In HD 100546 we got a signal shifted in 0.2 mas which is consistent with a keplerian disk accretion which was simulated in a geometrical model, and is consistent to the result of the paper of Mendigutía et al. 2015 using spectro-interferometry with AMBER.

Andreas Reisenegger Pontificia Universidad Católica

Old neutron stars still shine

Passive cooling processes of neutron stars are expected to make their thermal emission undetectable within less than 10 Myr. However, some reheating mechanisms might allow them to shine for a much longer time. One of the most effective ones is "rotochemical heating", which I proposed in Reisenegger (1995) and have studied in detail with various collaborators. Likely thermal emission from one Gyr-old millisecond pulsar was detected in HST observations (Kargaltsev et al. 2004; Durant et al. 2012). Ongoing HST observations aim to find it in 3 other pulsars, in order to test the models. Here, I will describe ongoing work on the theory and observations.

Andreas Reisenegger PUC & Chilean Representative in the CTA Consortium Board

Chilean participation in the Cherenkov Telescope Array (CTA) project

The CTA is the next-generation high-energy gamma-ray observatory, aimed at photons around 1 TeV energy, with unprecedented sensitivity and spatial resolution. It will in fact consist of two arrays, one of ~100 telescopes, likely near Cerro Armazones in Chile, and another of ~20 telescopes on La Palma island in Spain. Chile is a member of the CTA Consortium, with about 30 member scientists from 7 different universities. In this talk, I will briefly discuss the main aspects of the planned or already starting Chilean participation in this project.

Amber Roberts Universidad de Chile

Simulated absorption signals in quasar(QSO)-galaxy(GAL) pairs

Characterizing the distribution and physical properties of gas in the circum-galactic medium (CGM) around high redshift galaxies is key in order to understand the "baryon cycle" of accretion, star formation, chemical enrichment, and outflows that drives galaxy evolution. The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) will find roughly 600,000 galaxies at 1.8

Ósmar Rodríguez Universidad Nacional Andrés Bello

Type II supernovae as distance indicators at near-infrared wavelengths

We investigate the potential of Type II supernovae (SNe II) as distance indicators at near-infrared wavelengths. For this we work with the near-infrared photometry and optical spectroscopy of 17 nearby SNe II. We construct a near-infrared Hubble diagram, measuring distances with the method described in Rodríguez, Clocchiatti & Hamuy (2014). The dispersion of 0.13 mag in the Hubble diagram indicates a distance precision of 6%, comparable to the current precision of SN Ia distances.

Karina Rojas Universidad de Valparaiso

Quasar accretion disks: size and temperature profile using microlensing

We estimate the size and temperature profile of the quasar accretion disk using chromatic microlensing measurements. Microlensing magnification depend on the size of the microlens (the smaller is the source, the larger is the magnification). Spectroscopy data allow us to compare the magnitude difference between lensed images in the continum (affected by microlensing) and in the narrow emission lines (not affected by microlensing). The accretion disk was model as a Gaussian source, where the size of the disk is proportional to wavelength (r_s prop lambda^p, thin disk theory). The values obtained for the size and the temperature profile (p) are compared with previous results. We found that the sizes are in agreement with previous results, but are larger than expected from the prediction, and p generally is in agreement with the theory within errors.

Alexandre Roman-Lopes Universidad de La Serena

The W3/4/5 Super Star Forming Complexes: Unraveling Multiple Massive Star Populations with SDSS-IV/APOGEE spectrograph

In this contribution I will present a SDSS-IV ancillary program aimed to perform integrated spectroscopic study of the three Galactic massive star forming complexes W3, W4 and W5. For the first time we will be able to access simultaneously the massive stellar population together with a significative fraction of the massive YSO population. To date very few comprehensive highly homogeneous spectral studies of star forming complexes incorporating a large number of stars have been performed, particularly at high spectral resolution from which radial velocities can be measured. These complexes also provide an ideal laboratory to study spatially segregated formation of stars and the triggering mechanisms, such as the collection and collapse of massive molecular clumps. 92

Cristina Romero-Canizales Pontificia Universidad Católica

AGN activity in the advanced merger IC883

The interaction/merging of galaxies generate extreme conditions for the gas and dust, stemming intense periods of star formation, often accompanied by the presence of some sort of AGN activity. This is the case of luminous and ultra-luminous infrared galaxies (LIRGs: L_IR > 10^11 Lsun ; ULIRGs: L_IR > 10^12 Lsun), which represent excellent laboratories to study the starburst-AGN connection and the evolution of galaxies. The direct detection of both AGN and starburst is often compromised by the large amounts of dust in such galaxies and the compactness of their nuclei. Extinction-free, high-resolution observations such as those obtained with VLBI are key to unveil the true nature of these galaxies. In this talk I will present new exciting results from the LIRG IC883 in which we have detected AGN activity for the first time, this being at odds with its optical and IR spectral energy distribution. This example shows how important radio observations are to help us build a more complete view of these dusty objects.

Monica Rubio Universidad de Chile

Dense Cloud Cores revealed by ALMA CO observations in the low metallicity dwarf galaxy WLM

Understanding stellar birth requires observations of the clouds in which they form. These clouds are dense and self-gravitating, and in all existing observations, they are molecular with H2 the dominant species and CO the best available. When the abundances of carbon and oxygen are low compared to hydrogen, and the opacity from dust is also low, as in primeval galaxies and local dwarf irregular galaxies CO forms slowly and is easilydestroyed, so it cannot accumulate inside dense clouds. Then we lose our ability to trace the gas in regions of star formation and we lose critical information on the temperatures,densities, and velocities of the material that collapses. I will report on high resolution observations with ALMA of CO clouds in the local group dwarf irregular galaxy WLM, which has a metallicity that is 13% of the solar value and 50% lower than the previous CO detection threshold and the properties derived of very small dense CO clouds mapped.

Carolina Sabín-Sanjulián Universidad de La Serena

Properties of the O dwarf population in 30 Doradus

We aim at investigating the properties of a statistically significant sample of O dwarf stars in order to clarify some of the long-standing open questions concerning the main sequence of massive stars. For this purpose, we perform a comprehensive quantitative spectroscopic study of a sample of more than 100 O dwarf stars located within the 30 Dor region (LMC), identified by the VLT-FLAMES Tarantula Survey. We determine stellar and wind parameters by using the IACOB-GBAT tool, an automatic procedure based on an extensive grid of FASTWIND atmosphere models. The Bayesian tool BONNSAI is also used for the determination of evolutionary masses. We provide a new spectral calibration for effective temperatures of O dwarfs in the LMC, based on the most complete sample up to date. Most of the fast rotators found in our sample show a relative youth that evolutionary models for single stars cannot explain, thus leading us to think of a binary origin. We find a systematic difference between spectroscopic and evolutionary masses, which cannot be classified as a true discrepancy due to large error bars. Finally, the WLR distribution for our sample shows a large dispersion at high luminosities, and for luminosities below log(L/L_Sun)= 5.1 dex we could not determine properly the wind strength for our stars, so UV diagnostics becomes necessary."The spectroscopic orbit of HD54662 revisited"We use new high resolution and multi-epoch spectroscopic data, obtained mostly within the OWN Spectroscopic Survey, to investigate the properties of the double-lined binary HD54662, located in the Canis Major OB1 association, in the Seagull nebula complex. We apply a spectral disentangling method in order to obtain the individual spectra of both components, which are classified as an O7.5Vz and an O6.5Vz(n). We obtain an orbital period of P=5.80 yr, which makes HD54662 one of the longest period O+O binary systems known up to date. We also estimate radial velocities and minimum masses. We estimate the projected rotational velocities of both components by means of the IACOB-BROAD tool, which combines Fourier Transform and Goodness-Of-Fit methodologies. We perform a quantitative spectroscopic analysis of both components by means of the IACOB-GBAT tool, an automatic procedure based on a large grid of FASTWIND models that compares observed and synthetic optical H and He lines by means of a chi^2 algorithm. We determine stellar and wind parameters for both stars and investigate their properties in an evolutionary scenario.

Ricardo Salinas Gemini Observatory

The giant awakes: globular clusters in the nearest elliptical Maffei 1

Globular clusters are the treasure trove of stellar dynamics and evolution. As such they help us to answer a variety of astrophysical questions. In this talk I will present first results of the work of my summer students: the unveiling of the globular cluster system of our nearest elliptical galaxy, Maffei 1; and the influence of short-period variable stars in the intermediate age LMC clusters related to the phenomenon of extended main sequences. An outlook of the possibilities these systems give us will be presented.

Paula Sánchez Universidad de Chile

Characterization of the AGN variability in the optical and near infrared regimes

Variability is one of the most defining characteristic of Active Galactic Nuclei (AGN), and it is observed in every waveband in which they have been studied. For this reason variability studies are fundamental to understand the extreme physical conditions of accretion disks near supermassive black holes. Several efforts have been done to analyze the variability in the optical range, however, in order to relate the variability and physical properties of AGN, we need well sampled light curves. On the other hand, very little is known about the variability in the infrared range. This waveband gives us information about the dust surrounding the accretion disk at low redshift, and about the accretion disk at high redshift. In this talk, we will present the current status of our QUEST-La Silla AGN variability survey. This is an effort to obtain well sampled optical light curves of AGN in extragalactic fields with unique multiwavelength observations, using the QUEST camera on the ESO-Schmidt telescope.The survey uses a broadband filter, the Q-band, similar to the union of the g and the r filters. In particular, we will present the status of the analysis of the COSMOS, ELAIS-S1 and Stripe82 fields. Besides, we will present our statistical study of the near infrared (NIR) variability of AGN in the COSMOS field, using UltraVISTA data. This dataset give us a huge sample of light curves, making possible to have a global description of the nature of AGNs for different ranges of redshift, and for different levels of obscuration. By using both surveys, we expect to have a better understanding of the difference between type 1 and type 2 AGN. 97

Patricia Sanchez-Blazquez Pontificia Universidad Católica

Spatially resolved stellar populations with CALIFA

One of the most fundamental challenges in astrophysics is to understand the origin for the observed diversity of galaxies, and the physical mechanisms that are responsible for the differences as well as similarities between them. There is a modern agreement among astronomers that a variety of processes play a role in shaping galaxies, for example gas accretion, feedback, in-situ star formation,mergers, and dynamical processes such as diffusion and migration of stars. The detailed manner in which these processes proceed ultimately determines the kinematics, star formation history (SFH)and chemical structure of galaxies. The technical possibilities of Integral Field Spectroscopy (IFS)have the potential to provide a tremendous boost in the field as we will be able to obtain information on the whole galaxy, not just of their central parts. Several ongoing and projected IFS surveys are studying the star formation histories in nearby galaxies. In this talk I will provide an overview of the latest results obtained as part of the CALIFA collaboration.

Gary Sanders Thirty Meter Telescope Project

Thirty Meter Telescope: Review and status

Pedro Sanhueza Oficina de Protección de la Calidad del Cielo

Starting the implementation Of the new Light Pollution Norm

100

Luca Sbordone Pontificia Universidad Católica

Chemical analysis of the GIBS UVES sample: Li-rich giants towards the Bulge

We report on the work in progress to determine the detailed composition of a sample of ~100 inner- disk giants observed with FLAMES-UVES, mostly during the ESO Large Program GIBS (Giraffe Inner Bulge Survey, Zoccali et al., 2014). The spectra cover the 480-680 nm range at R=47000, with a S/N between 50 and 100 per pixel. Atmosphere parameters and composition for 21 species of 18 elements have been determined automatically by means of the MyGIsFOS code, showing a prevailing metal rich sample with a few possible thick disk / halo interlopers. Abundance of α elements seems to follow the usual Milky Way disk pattern, with a few star possibly belonging to the so-called high alpha metal rich (HAMR) class.Part of the sample was deliberately targeting candidate lithium-rich giants, and indeed a few stars display extremely strong Li features, consistent with super-ISM abundance. 101

Dominik Schleicher Universidad de Concepción

Structure formation in the early Universe

The first structures in the Universe are expected to form at redshifts of z~15-20, including the formation of the first stars, galaxies and supermassive black holes. The very first of these objects form from a primordial gas consisting of hydrogen and helium, while second-generation objects may be subject to metal-enrichment. I will present 3D simulations following structure formation under different chemical conditions, including primordial gas with and without radiation backgrounds, as well as the gas after metal enrichment. Based on these simulations, I will discuss the mass scales of the first cosmological objects that can be obtained in different environments.

102

Alberto Sesana University of Birmingham

Lessons on massive black hole binary astrophysics from pulsar timing arrays

The detection of gravitational waves (GWs) may soon be a reality,opening a completely new window on the Universe. At nHz frequencies,pulsar timing arrays (PTAs) promise to detect the signal coming from the cosmological population of supermassive black hole binaries (SMBHBs) within the next few years. After reviewing the astrophysics of SMBHBs, I will describe the current status of the PTA effort, present the most recent limits, and their astrophysical implications.

103

R. Chris Smith AURA Observatory

Update on LSST and other AURA Facilities

LSST is under construction at the AURA Observatory site on Cerro Pachon. I will provide an update on the status and planning for this new facility as well as updates on other instruments and telescopes available as part of the AURA Observatory in Chile.

104

Maritza Soto Universidad de Chile

Searching for transiting planets in the south

NGTS is a wide-field photometric survey design to detect transiting Neptune size planets or smaller orbiting bright K dwarfs in the southern hemisphere. NGTS first light was obtained in the second half of 2015, and it consists of an array of small telescopes that operate remotely from the Paranal Observatory. In my presentation I will show the first preliminary results from this survey, as well as the follow up and characterization that will be needed after the first candidates are selected. This follow up work will be a good opportunity for the Chilean community to get involved in this project.

105

Piera Soto King Universidad de La Serena

Star formation in the area of VVV clusters La Serena 210, 211 and 212

In this work, we present a deep multi-band photometric study of a star forming region that harbors the new VVV clusters La Serena, 210, 211 and 212 (Barbá et al. (2015)). The area analyzed covers about 40'×40’ and it is located on the Galactic plane at l = 321°. The region is a complex structure formed by large filamentary dark clouds, cataloged as IRDC 321.706 + 0.066 (Vasyunina et al. (2009, 2011, 2014)), and which hosting an active star formation. Regarding this dust filaments, a notable contrast with the surrounding medium is noticed even at mid-infrared wavelengths. The current star formation is characterized for thepresence of the embedded VVV clusters La Serena 210, 211,212. We have performed a complete photometric analysisusing the near-infrared VVV images, which were complemented with additional datasets as 2MASS (Skrutskie et al., 2006), GLIMPSE (Benjamin et al. , 2003), WISE (Wrightet al. , 2010), MIPS-24μm (Rieke et al. , 2004) and ATLASGAL (Schuller et al. , 2009). We have determined the spectral energy distribution (SED) for the more noticeable cluster members which allows us to characterize the stellar content and the evolutionary stage of clusters, based in the SED models provided by Robitaille et al. (2006), andthe classification scheme for young stellar objects proposedby Gutermuth et al. (2009). The mean distance that wasobtained have concordance with the kinematic distance provided by Vasyunina et al. (2009) and García et al. (2014) (aprox. 2.2 kpc) for the IRDC.Furthermore , it is presented extinction maps of the darks clouds, which allow to map the filamentary structures and condensations detected at sub-mm wavelengths, the regions that presented more extinction have spatial coincidence with the star forming regions inside the molecularcloud.

106

Katalin Takats Universidad Nacional Andrés Bello

Searching for the progenitor of SN 2009ib

SN 2009ib was a Type II-P supernova (SN) in NGC 1559. Its host galaxy was observed by the Hubble Space Telescope in 2001, which gave us an opportunity to look for the progenitor of the SN directly. However the HST images were not particularly deep and the galaxy is relatively far for this kind of analysis, so our study resulted in several open questions. Therefore we obtained new HST images in November 2015, which are going to help us to find answers to at least some of the questions. In my talk I'll present the results of our analysis of both the old and the new HST images and discuss the possible progenitor of SN 2009ib. 107

Claus Tappert Universidad de Valparaiso

The mass-tranfer rates of old novae

Nova eruptions play a pivotal role in the evolution of cataclysmic variables (CVs), because they represent the primary mechanism for mass loss in these interacting binary stars. It is also widely assumed that they are followed by a phase of increased mass-transfer rate that lasts several centuries, due to irradiation of the donor star by the eruption-heated white-dwarf accretor. In my talk I will review the observational evidence for and against this scenario.

108

Ezequiel Treister Universidad de Concepción

The Role of Major Galaxy Mergers in Black Hole Growth and Galaxy Evolution

Theoretical studies strongly suggest that there is a strong connection between major mergers of gas- rich galaxies and significant supermassive black hole (SMBH) growth episodes. Furthermore, these episodes can lead to significant energy outputs, which in turn can heat up or remove molecular gas contents, thus stopping ongoing and future star formation.

In this talk I will review the main observational results obtained as part of the CONICYT’s EMBIGGEN Anillo program, involving researchers at UdeC, PUC and UChile. Specifically, I will focus on the ALMA, VLT/MUSE and VLT/SINFONI data obtained for a sample of 6 nearby dual AGN (two merging galaxies hosting SMBHs growing simultaneously, separated by <10 kpc), including the archetypical merging system NGC6240. Clear evidence for outflows and feedback effects can be seen in the MUSE optical IFU data.

Then, I will discuss the main results of a NuSTAR AO-1 cycle aimed to obtain high energy observations for a sample of 12 nearby galaxies undergoing major mergers in the Local Universe at high energies. These data allow us to detect even heavily obscured SMBH growth episodes, including the detection for the first time of a hidden AGN in NGC6286.

The importance of these high-luminosity, merger-triggered, obscured BH growth episodes, identified in the IR as ULIRGs, for the cosmic history of BH growth and its connection to galaxy evolution will be discussed.

109

Paulina Troncoso Iribarren Pontificia Universidad Católica

Asymmetric star formation in dense enviroment as evidence for ram pressure stripping

As galaxies plunge into the ICM of groups and clusters of galaxies, they experience different effects from their surrounding environment including ram pressure (RP) and tidal stripping. These are believed to produce changes in the satellite properties ranging from gas loss to enhanced star formation (SF) activity due to the increase pressure acting on the disc of the galaxy. In this work we explore statistical ways to detect such effects using large samples of galaxies in clusters and groups. We study each galaxy satellite by dividing it in half, the one that faces the medium as it moves through the ICM (leading half) and the one facing the opposite way (trailing half). We applied this method to SDSS and EAGLE simulated data measuring differences of up to 20%, depending on the orientation of the galaxy's major axis with respect to the cluster centre vector. We conclude that the effects of RP compression in the SF activity is of a timescale shorter than the dynamical time of the disc because the enhancement of the SF is more prominent in the leading half, which feels directly the effect of RP.

110

Jose Utreras Universidad de Chile

The impact of rotation on star forming galaxies

Knowing how efficiently stars are formed in galaxies is fundamental in order to understand the evolution of our universe. Despite the complexity of the star formation process, observations suggest that the star formation rate in a galaxy can be expressed in terms of global properties, such as average gas density (Schmidt 1959, Kennicutt 1998), although other relations have been proposed, which include orbital (Silk 1997, Elmegreen 1997) or effective free-fall times (Krumholz et al. 2012). However, the real effects of the parameters which control the formation of stars, such as rotation, is not completely understood.In this talk I will show results from simulations of spiral and starburst galaxies, confirming that the star formation history of each individual object can be represented by a dimensionally homogeneous relation suggested by observations (Escala 2015). Additionally we found a clear anti-correlation between rotation of galaxies and the star formation efficiency. Finally, we obtained a single star formation law for the whole sample, where its efficiency is an exponentially decreasing function of the product of the angular velocity and the initial free-fall time. These findings might help us to understand the effect of strong and weak external potentials on star formation, such as dark-matter dominated objects, and this functional form can be included in cosmological simulations where the star formation recipes rely on global properties due to their resolution requirements.

111

Millarca Valenzuela Pontificia Universidad Católica

Chilean Meteorites: their heritage status and present research

Atacama desert is not only the place with the clearest skies for astronomical observations; it is also the perfect place to store meteorites for thousand to millions of year on their old, dry and stable surfaces. These extraterrestrial rocks represent the building blocks of planets and other solid bodies of the Solar System, and the information they bring is crucial to understand planetary processes as accretion, chemical and physical differentiation, and other evolved processes as thermal and shock induced metamorphism, between others. At present the Chilean meteorite collection is dominated by ordinary chondrites, and with them we study the flux of extraterrestrial material to Earth in the last 2 million years that they represent. The preservation of this kind of world heritage scientific objects is a matter that we need to discuss, as many meteorites are collected every year without any restriction, losing important information. 112

Leonardo Vanzi Pontificia Universidad Católica

Astronomical Instrumentation at the AIUC

I will present the status and recent progress on Astronomical Instrumentation at the Center of Astro Engineering UC

113

Vicente Villanueva Universidad de Valparaiso

The molecular gas content in H-ATLAS galaxies up to z=0.4

We analyze ALMA Band-3 observations at ~3" resolution to detect the 12CO(1-0) emission of 68 z<0.4 "main-sequence" galaxies selected from Herschel-Astrophysical Terahertz Large Area Survey (H- ATLAS). The sample is extracted form the equatorial GAMA fields (α=9h, 12h and 15h , �=0º) where additional broad-band and spectroscopic multi-wavelength coverage is available, facilitating exploration over a wide parameter space including galaxy types, morphology, star-formation rate, stellar masses, etc. We have introduced a novel approach to optimize source imaging by fine tuning the spectral resolution to obtain the best compromise between signal to noise and source cleaning. Source extraction, aided by optical spectroscopic redshifts, revealed that more than 75% of the sample is detected in 12CO(1-0) permitting an estimate of the molecular gas mass (M_H2). Making use of the dust-obscured star-formation rates derived from the Herschel photometry in combination with M_H2, we are able to characterize their intimate relationship (at z<0.4) providing gas-consumption scales and "normal"/starburst classification. Approximately a third of the sample is resolved in CO by ALMA, providing an exploration of the Kennicutt-Schmidt law up to z~0.4 and finding little or no evolution of this classical relation. Two other main research lines have been born from this sample: first, the availability of PACS-[CII] spectroscopy in approximately half of the CO-detected sample allows detailed studies of the ISM content using PDR modelling; second, the identification of gas-rich galaxies (f_gas=M_H2/(M_H2+M_star)>0.3) at z<0.4, similar to those found at z~1-3, has triggered a detailed high-resolution follow-up campaign to understand the physics governing their star-formation.

114

Jaime Villaseñor Universidad de La Serena

B-type Giant and Supergiant Stars in the "Galactic O-type Star Spectroscopic Survey": Spectral Analysis

The ”Galactic O-type Star Spectroscopic Survey” (GOSSS), is an intermediate-resolution all-sky spectroscopic survey of O-type stars brighter than B = 14. GOSSS is also providing a huge database of hundreds of spectra of excellent quality of luminous B-type stars, many of them neighbours to O- type stars observed in the same slit. The luminous B-type stars are also massive stars but the UV power is not enough to ionize large volume of the interstellar medium (ISM). Early B-type stars are also important piece of the galactic evolution of the ISM because they will produce red supergiants in an advance stage of life and also core-collapse supernovae. We have found 896 B-type stars from which 382 giant and supergiant stars have been analyzed to determine their spectral type and luminosity class. In order to do this, we have followed the same scheme that we used in the three main GOSSS published papers (Sota et al., 2011, 2014, Maíz Apellániz et al. 2015), but we have also introduced a classification scheme for the luminosity class based in the ratios of lines of silicon ions to He I outlined in Gray and Corbally (2009). The results repeatedly show differences in classification compared with the literature, and in some cases these differences are large, particularly for the luminosity class. This work has deliver for the first time, a large sample of B-type giants and supergiants with spectral types and luminosity classes determined from spectrograms of uniform quality, high signal to noise, all homogeneously processed, and a complete sample of standard stars to help in the future classification of new observed B-type giants and supergiants. This work is part of the MsC thesis at Universidad de La Serena.

115

Joris Vos Universidad de Valparaiso

The unexpected eccentricity of long period hot subdwarf binaries.

Hot subdwarf-B (sdB) stars are core helium burning stars with a very thin hydrogen envelope (Menv < 0.02 Msun), and a mass close to the core helium flash mass ~ 0.47 Msun. sdB stars are formed by binary evolution only, where binary-interaction physics, e.g. common envelope ejection and stable Roche-Lobe overflow, play a major role. This makes them interesting objects for testing binary- evolution models, because they provide strong constraints on the final stellar parameters to ignite helium in their core. Most currently known long period sdB binaries have eccentric orbits, even though binary-evolution theory predicts them to have circularized before the onset of Roche-Lobe overflow (RLOF). We have tested several mechanisms to increase or re-introduce eccentricity in the orbit of long period binaries. A combination of eccentricity pumping during RLOF due to phase-dependent mass loss, and the interaction of the binary with a circumbinary disk formed during RLOF can explain the observed eccentricities of the long period sdB binaries. We have extended the evolution code MESA with the missing processes for eccentric orbital evolution, and implemented the model of Lubow & Artymowicz (1996) for the interaction between the binary and a circumbinary disk. By tweaking the parameters of this model, the observed orbital parameters can be explained, even though the exact period-eccentricity distribution of long period sdB binaries cannot be recreated.

116

Maja Vuckovic Universidad de Valparaiso

Asteroseismology of hot subdwarf stars

Ultra high-precision photometric data of pulsating hot subdwarf B (sdB) stars with the nominal Kepler space telescope have lead to the discovery of 18 new sdB pulsators. Many of these stars were observed continuously in short cadence for three years making them the best studied pulsating sdB stars to date. Discoveries from these data include nearly-evenly-spaced asymptotic period overtones and rotationally-induced frequency multiplets which have made it possible to identify pulsation modes and determine rotation rates. Now, with the Kepler two-wheel mission (K2), we are continuing the search for new pulsating sdBs along the ecliptic plane. Therefore, it is timely to interpret the unprecedented space data with the state-of-the-art theoretical models.I will present the current efforts in time series analysis and mode identification of sdB stars in the Kepler and K2 field of view. With the final aim of performing an in-depth asteroseismic modeling of individual sdB targets using the stellar structure and evolution code MESA, combined with the adiabatic and non-adiabatic linear pulsation code GYRE. With these tools, we are able to address the combined role of gravitational settling and the radiative levitation of heavy elements below the surface of sdBs. This approach provides an immediate improvement to the excitation mechanism of p- and g-modes in the envelopes of sdBs which is quite sensitive to the details of mixing mechanisms operating in radiative interior of these compact pulsators. 117

Manuela Zoccali Pontificia Universidad Católica

The Stellar Mass and Density Profile of the Galactic bulge

118

Monica Zorotovic Universidad de Valparaiso

Major problems of CV evolution and the existence of detached CVs in the period gap

The observed orbital period distribution of Cataclysmic Variables (CVs), the space density of CVs derived from observations, and the observed orbital period minimum are known to disagree with theoretical predictions since decades. More recently, the average white dwarf (WD) masses in CVs have been found to significantly exceed those of single WDs, which also is in contrast to theoretical expectations. I will show that all these problems can be solved if CVs with low-mass WDs are driven into dynamically unstable mass transfer due to consequential angular momentum loss that increases with decreasing WD mass.

I will also show the results of an observational search for close white-dwarf plus main-sequence binaries with the aim of testing if a peak in the orbital period distribution can be observed at the position of the famous orbital period gap (2-3 h). Such a peak could give us evidence of the existence of detached CVs in the period gap, in agreement with the predictions from the standard theory of CV evolution, i.e., the disrupted magnetic braking scenario.