DOCSLIB.ORG

Dissertation Submitted to the Combined Faculties of the Natural

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Dissertation Submitted to the Combined Faculties of the Natural Dissertation submitted to the Combined Faculties of the Natural Sciences and Mathematics of the Ruperto-Carola-University of Heidelberg, Germany for the degree of Doctor of Natural Sciences Put forward by Mikhail Kovalev born in: Kursk, USSR Oral examination:11.11.2019 NLTE analysis of the Gaia-ESO spectroscopic survey. Referees: Dr. Maria Bergemann Prof. Dr. Andreas Quirrenbach 2 Abstract ZUSAMMENFASSUNG: In dieser Arbeit entwickeln wir eine Pipeline zur spektralen Analyse, die synthetischen NLTE Spektren mit the Payne (Ting et al. 2018) Spektralmodel kombiniert. Wir berechnen zwei spektrale Gitter, in einem der Gitter werden alle Elemente mit LTE behandelt und das zweite Gitter wird unter Verwendung von Eisen, Magnesium, Titan und Mangan mit NLTE modelliert, um NLTE Effekte auf die Bestimmung stellarer Parameter und Elementh¨aufigkeiten zu untersuchen. Diese Pipeline wird auf Spektren aus der dritten ¨offentlichen Datenver¨offentlichung von Gaia-ESO (Gilmore et al. 2012) angewandt. Wir pr¨ufen unsere Methodik mit einer Stichprobe von Standardsternen und Mitgliedern von Sternhaufen und finden signifikante Unterschiede zwischen NLTE und LTE im metallarmen Bereich. Die Elementhufigkeiten von Eisen und Titan sind homogen in allen Sternhaufen, aber mehrere Kugelsternhaufen zeigen eine signifikante Dispersion f¨ur[Mg/Fe]. Die Verringerung des mittleren [Mg/Fe] in einigen Kugelsternhaufen, im Vergleich zu Feldsternen mit vergleichbarer Metallizit¨at,deuten m¨oglicherweise eine ex-situ Entstehungsgeschichte an. Wir kombinieren unsere NLTE Resultate auch mit den astrometrischen Daten des Gaia DR2 (Gaia Collaboration et al. 2018), um die chemo-dynamische Entwicklung der Milchstraße zu untersuchen. Wir nutzen die Unterschiede in der chemischen Zusammensetzung, um Scheibenpopulationen mit hohem [α=Fe] und niedrigem [α=Fe] zu unterscheiden. Halo Sterne werden durch Unterschiede in der Kinematik ausgew¨ahlt. Wir best¨atigenfr¨uhereErgebnisse, wie eine h¨ohere Elementh¨aufigkeit von Mg im Vergleich zur Sonne im metallarmen Bereich und einen Abfall von [Mg/Fe] im Vergleich zur Sonne im metallreichen Bereich. Wir finden ein konstantes NLTE [Mg/Fe] ∼ 0:3 dex Verh¨altnissowohl fr die metallarme Scheibe als auch den Halo mit relativ kleiner Streuung zwischen einzelnen Sternen. Die Halo Sterne mit [Mg/Fe] vergleichbar zur Sonne wurden wahrscheinlich von anderen Galaxien eingefangen. Die beobachtete Exzentrizit¨atsverteilung f¨urhohe [α=Fe] Scheiben Populationen schließt einen gewaltsamen Formationsmechanismus f¨urdie dicke Scheibe wie direkte Akkretion und dynamische Anregung aus. Die gemessenen chemischen und kinematischen Gradienten und Geschwindigkeitsdispersionen der Populationen mit hohem [α=Fe] k¨onnenmit gasreichen Mergern erkl¨artwerden, wobei radiale Migration nicht zu vernachlssigen ist. ABSTRACT: In this work, we develop the spectral analysis pipeline that combines the NLTE synthetic spectra with the Payne spectral model (Ting et al. 2018). We compute two spectral grids, one grid with all elements treated in LTE and a second grid with iron, magnesium, titanium and manganese modelled in NLTE, to study the NLTE effects on the determination of the stellar parameters and chemical 3 abundances. This pipeline is applied to spectra from the third public data release of the Gaia-ESO (Gilmore et al. 2012). We validate the method on the subsample of standard stars and cluster's members and find significant differences between NLTE and LTE in the metal-poor regime. All clusters are homogeneous in Fe and Ti, but several globular clusters showed significant dispersion in [Mg/Fe]. The depletion of the mean [Mg/Fe] in several globular clusters, compared to field stars of the same metallicity, may indicate their ex-situ formation history. We also combine our NLTE results with Gaia DR2 (Gaia Collaboration et al. 2018) astrometric data to study Galactic chemo-dynamic evolution. We apply chemical separation to select high-[α=Fe] and low-[α=Fe] disk populations, with halo stars selected using kinematics. We confirm previous results like super-solar Mg abundance in the metal-poor regime and decrease of [Mg/Fe] to the solar abundances in the metal-rich regime. We find a constant NLTE [Mg/Fe]∼ 0:3 dex ratio for both metal-poor disk and halo with relatively small star-to-star scatter. The halo stars with solar-like [Mg/Fe] are probably accreted from the other galaxies. The observed eccentricity distribution for high-[α=Fe] disk population rules out a violent thick disk formation mechanisms like direct accretion and dynamic heating. The measured chemical and kinematic gradients and velocity dispersions of the high-[α=Fe] population can be explained by the gas-rich merger scenario with the non-negligible contribution from the radial migration. 4 Contents Abstract3 List of Figures8 List of Tables 11 Acknowledgments 14 1 Introduction1 1.1 Motivation.................................1 1.2 Theoretical basis of spectral modelling.................2 1.3 Analysis of observed spectra.......................8 1.3.1 Machine learning in spectroscopy................ 10 1.4 The Milky Way structure......................... 13 1.5 Kinematic properties of the stars.................... 15 1.5.1 Galactocentric coordinates and velocities............ 15 1.6 Probing the thick disk formation scenarios............... 17 1.7 This thesis................................. 18 2 NLTE Chemical abundances in Galactic open and globular clusters 21 2.1 Introduction................................ 21 2.2 Methods.................................. 23 5 CONTENTS 2.2.1 Observed spectra......................... 23 2.2.2 Instrumental profile........................ 23 2.2.3 Radial velocities.......................... 24 2.2.4 Model atmospheres and synthetic spectra............ 25 2.2.5 The Payne code.......................... 26 2.2.6 Internal accuracy of the method................. 28 2.3 Results................................... 31 2.3.1 Gaia-ESO benchmark stars................... 31 2.3.2 Open and globular clusters.................... 34 2.4 Discussion................................. 46 2.4.1 Comparison with the literature................. 46 2.4.2 Comparison with Milky Way field stars............. 58 2.5 Conclusions................................ 62 3 Analysis of Gaia-ESO Milky Way field stars 67 3.1 Introduction................................ 67 3.2 Spectral sample.............................. 69 3.3 Kinematic and dynamics.......................... 70 3.4 Galactic population selection....................... 73 3.5 Survey selection function and an impact of the parallax quality cut. 78 3.6 Results................................... 80 3.6.1 Eccentricity and metallicity distributions............ 80 3.6.2 Orbital properties......................... 81 3.6.3 Chemical gradients with R and jZj ............... 82 3.6.4 Velocity gradients with R, jZj and [Fe/H]............ 84 3.6.5 Velocity and velocity dispersions with [α/Fe].......... 87 3.7 Discussion................................. 88 6 CONTENTS 3.7.1 Comparison with stellar clusters................. 88 3.7.2 Formation of the thick disk................... 90 3.8 Summary and conclusions........................ 95 4 NLTE online-service 99 4.1 Introduction................................ 99 4.2 Methods.................................. 100 4.3 Functionality............................... 101 4.4 Summary and future plans........................ 102 5 Summary 105 5.1 Perspectives................................ 107 List of publications 109 References 111 7 CONTENTS 8 List of Figures 1.1 Example of simple ANN with one fully-connected hidden layer. Figure credit Bailer-Jones et al.(1997)..................... 11 1.2 Schematic description of the Payne ANN................ 13 1.3 Schematic side-view of the Galaxy. (not to scale)........... 14 1.4 Galactocentric Cartesian system definition................ 15 1.5 Eccentricity distributions as a probe of the thick disk formation sce- nario. Figure credit Sales et al.(2009)................. 18 2.1 HR10 instrumental profile......................... 24 2.3 Sensitivity of the method to the quality of the spectra......... 33 2.4 The mean NLTE-LTE difference..................... 36 2.5 NLTE results compared to isochrones.................. 37 2.6 LTE results compared to isochrones................... 38 2.7 Example of NLTE/LTE spectral fit 1.................. 39 2.8 Example of NLTE/LTE spectral fit 2.................. 40 2.9 NLTE abundances as a function of Teff .................. 42 2.10 Abundances as a function of Teff and the Teff -log(g) diagram for the open cluster NGC 2243.......................... 44 2.11 Comparison of the spectra of two M 15 stars with different [Mg/Fe].. 44 2.12 The Toomre diagram for the clusters................... 59 9 LIST OF FIGURES 2.13 Mean LTE metallicities and [Mg/Fe] and [Ti/Fe] abundance ratios for all clusters and for Milky Way field stars................. 61 2.14 Mean NLTE metallicities and [Mg/Fe] and [Ti/Fe] abundance ratios for all clusters and for Milky Way field stars.............. 61 2.15 The average abundance ratios of the clusters in comparison with the Galactic halo, thick disk, and three dSph galaxies............ 63 3.1 The Galactic coordinates for stars in our sample............ 70 3.2 The Gaia colour-magnitude diagram and The Kiel diagram for our sample of GES MW field stars...................... 71 3.3 The distribution of the distance sampling for two stars......... 72 3.4 The uncertainties for cylindrical coordinates and velocities....... 72 3.5 The spatial and kinematic distributions for
Load more

Recommended publications
  • XMM-Newton Observations of the Galactic Globular Clusters NGC 2808 and NGC 4372
    A&A 480, 397–407 (2008) Astronomy DOI: 10.1051/0004-6361:20078327 & c ESO 2008 Astrophysics XMM-Newton observations of the Galactic globular clusters NGC 2808 and NGC 4372 M. Servillat, N. A. Webb, and D. Barret CESR, Université Paul Sabatier, CNRS, 9 avenue du Colonel Roche, 31400 Toulouse, France e-mail: [email protected] Received 20 July 2007 / Accepted 28 November 2007 ABSTRACT Aims. Galactic globular clusters harbour binary systems that are detected as faint X-ray sources. These close binaries are thought to play an important role in the stability of the clusters by liberating energy and delaying the inevitable core collapse of globular clusters. The inventory of close binaries and their identification is therefore essential. Methods. We present XMM-Newton observations of two Galactic globular clusters: NGC 2808 and NGC 4372. We use X-ray spectral and variability analysis combined with ultra-violet observations made with the XMM-Newton optical monitor and published data from the Hubble Space Telescope to identify sources associated with the clusters. We compare the results of our observations with estimates from population synthesis models. Results. Five sources out of 96 are likely to be related to NGC 2808. Nine sources are found in the field of view of NGC 4372, none being located inside its half-mass radius. We find one quiescent neutron star low mass X-ray binary candidate in the core of NGC 2808, and propose that the majority of the central sources in NGC 2808 are cataclysmic variables. An estimation leads to 20±10 cataclysmic variables with luminosity above 4.25 × 1031 erg s−1.
    [Show full text]
  • A Basic Requirement for Studying the Heavens Is Determining Where In
    Abasic requirement for studying the heavens is determining where in the sky things are. To specify sky positions, astronomers have developed several coordinate systems. Each uses a coordinate grid projected on to the celestial sphere, in analogy to the geographic coordinate system used on the surface of the Earth. The coordinate systems differ only in their choice of the fundamental plane, which divides the sky into two equal hemispheres along a great circle (the fundamental plane of the geographic system is the Earth's equator) . Each coordinate system is named for its choice of fundamental plane. The equatorial coordinate system is probably the most widely used celestial coordinate system. It is also the one most closely related to the geographic coordinate system, because they use the same fun­ damental plane and the same poles. The projection of the Earth's equator onto the celestial sphere is called the celestial equator. Similarly, projecting the geographic poles on to the celest ial sphere defines the north and south celestial poles. However, there is an important difference between the equatorial and geographic coordinate systems: the geographic system is fixed to the Earth; it rotates as the Earth does . The equatorial system is fixed to the stars, so it appears to rotate across the sky with the stars, but of course it's really the Earth rotating under the fixed sky. The latitudinal (latitude-like) angle of the equatorial system is called declination (Dec for short) . It measures the angle of an object above or below the celestial equator. The longitud inal angle is called the right ascension (RA for short).
    [Show full text]
  • High-Precision Asteroseismology of Dense Stellar Fields
    Experimental Astronomy https://doi.org/10.1007/s10686-021-09711-1 ORIGINAL ARTICLE HAYDN High-precision AsteroseismologY of DeNse stellar fields Andrea Miglio1,2,3 · Leo´ Girardi4 · Frank Grundahl5 · Benoit Mosser6 · Nate Bastian7 · Angela Bragaglia3 · Karsten Brogaard5,8 · Gael¨ Buldgen9 · William Chantereau7 · William Chaplin1 · Cristina Chiappini10 · Marc-Antoine Dupret11 · Patrick Eggenberger9 · Mark Gieles12,13 · Robert Izzard14 · Daisuke Kawata15 · Christoffer Karoff5 · Nadege` Lagarde16 · Ted Mackereth1,17,18,19 · Demetrio Magrin4 · Georges Meynet9 · Eric Michel20 · Josefina Montalban´ 1 · Valerio Nascimbeni4 · Arlette Noels11 · Giampaolo Piotto21 · Roberto Ragazzoni4 · Igor Soszynski´ 22 · Eline Tolstoy23 · Silvia Toonen1,24 · Amaury Triaud1 · Fiorenzo Vincenzo1,25 Received: 29 July 2020 / Accepted: 9 February 2021 / © The Author(s) 2021 Abstract In the last decade, the Kepler and CoRoT space-photometry missions have demon- strated the potential of asteroseismology as a novel, versatile and powerful tool to perform exquisite tests of stellar physics, and to enable precise and accurate char- acterisations of stellar properties, with impact on both exoplanetary and Galactic astrophysics. Based on our improved understanding of the strengths and limitations of such a tool, we argue for a new small/medium space mission dedicated to gath- ering high-precision, high-cadence, long photometric series in dense stellar fields. Such a mission will lead to breakthroughs in stellar astrophysics, especially in the metal poor regime, will elucidate the evolution and formation of open and globular clusters, and aid our understanding of the assembly history and chemodynamics of the Milky Way’s bulge and a few nearby dwarf galaxies. Keywords Stars: low-mass · Globular clusters · Galaxy: bulge · Galaxies: dwarf · Asteroseismology A list of people who have expressed interest for HAYDN is available here: https://www.asterochronometry.eu/haydn/people.html Andrea Miglio [email protected] Extended author information available on the last page of the article.
    [Show full text]
  • ESO Annual Report 2004 ESO Annual Report 2004 Presented to the Council by the Director General Dr
    ESO Annual Report 2004 ESO Annual Report 2004 presented to the Council by the Director General Dr. Catherine Cesarsky View of La Silla from the 3.6-m telescope. ESO is the foremost intergovernmental European Science and Technology organi- sation in the field of ground-based as- trophysics. It is supported by eleven coun- tries: Belgium, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Sweden, Switzerland and the United Kingdom. Created in 1962, ESO provides state-of- the-art research facilities to European astronomers and astrophysicists. In pur- suit of this task, ESO’s activities cover a wide spectrum including the design and construction of world-class ground-based observational facilities for the member- state scientists, large telescope projects, design of innovative scientific instruments, developing new and advanced techno- logies, furthering European co-operation and carrying out European educational programmes. ESO operates at three sites in the Ataca- ma desert region of Chile. The first site The VLT is a most unusual telescope, is at La Silla, a mountain 600 km north of based on the latest technology. It is not Santiago de Chile, at 2 400 m altitude. just one, but an array of 4 telescopes, It is equipped with several optical tele- each with a main mirror of 8.2-m diame- scopes with mirror diameters of up to ter. With one such telescope, images 3.6-metres. The 3.5-m New Technology of celestial objects as faint as magnitude Telescope (NTT) was the first in the 30 have been obtained in a one-hour ex- world to have a computer-controlled main posure.
    [Show full text]
  • Arxiv:2006.10868V2 [Astro-Ph.SR] 9 Apr 2021 Spain and Institut D’Estudis Espacials De Catalunya (IEEC), C/Gran Capit`A2-4, E-08034 2 Serenelli, Weiss, Aerts Et Al
    Noname manuscript No. (will be inserted by the editor) Weighing stars from birth to death: mass determination methods across the HRD Aldo Serenelli · Achim Weiss · Conny Aerts · George C. Angelou · David Baroch · Nate Bastian · Paul G. Beck · Maria Bergemann · Joachim M. Bestenlehner · Ian Czekala · Nancy Elias-Rosa · Ana Escorza · Vincent Van Eylen · Diane K. Feuillet · Davide Gandolfi · Mark Gieles · L´eoGirardi · Yveline Lebreton · Nicolas Lodieu · Marie Martig · Marcelo M. Miller Bertolami · Joey S.G. Mombarg · Juan Carlos Morales · Andr´esMoya · Benard Nsamba · KreˇsimirPavlovski · May G. Pedersen · Ignasi Ribas · Fabian R.N. Schneider · Victor Silva Aguirre · Keivan G. Stassun · Eline Tolstoy · Pier-Emmanuel Tremblay · Konstanze Zwintz Received: date / Accepted: date A. Serenelli Institute of Space Sciences (ICE, CSIC), Carrer de Can Magrans S/N, Bellaterra, E- 08193, Spain and Institut d'Estudis Espacials de Catalunya (IEEC), Carrer Gran Capita 2, Barcelona, E-08034, Spain E-mail: [email protected] A. Weiss Max Planck Institute for Astrophysics, Karl Schwarzschild Str. 1, Garching bei M¨unchen, D-85741, Germany C. Aerts Institute of Astronomy, Department of Physics & Astronomy, KU Leuven, Celestijnenlaan 200 D, 3001 Leuven, Belgium and Department of Astrophysics, IMAPP, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands G.C. Angelou Max Planck Institute for Astrophysics, Karl Schwarzschild Str. 1, Garching bei M¨unchen, D-85741, Germany D. Baroch J. C. Morales I. Ribas Institute of· Space Sciences· (ICE, CSIC), Carrer de Can Magrans S/N, Bellaterra, E-08193, arXiv:2006.10868v2 [astro-ph.SR] 9 Apr 2021 Spain and Institut d'Estudis Espacials de Catalunya (IEEC), C/Gran Capit`a2-4, E-08034 2 Serenelli, Weiss, Aerts et al.
    [Show full text]
  • FY13 High-Level Deliverables
    National Optical Astronomy Observatory Fiscal Year Annual Report for FY 2013 (1 October 2012 – 30 September 2013) Submitted to the National Science Foundation Pursuant to Cooperative Support Agreement No. AST-0950945 13 December 2013 Revised 18 September 2014 Contents NOAO MISSION PROFILE .................................................................................................... 1 1 EXECUTIVE SUMMARY ................................................................................................ 2 2 NOAO ACCOMPLISHMENTS ....................................................................................... 4 2.1 Achievements ..................................................................................................... 4 2.2 Status of Vision and Goals ................................................................................. 5 2.2.1 Status of FY13 High-Level Deliverables ............................................ 5 2.2.2 FY13 Planned vs. Actual Spending and Revenues .............................. 8 2.3 Challenges and Their Impacts ............................................................................ 9 3 SCIENTIFIC ACTIVITIES AND FINDINGS .............................................................. 11 3.1 Cerro Tololo Inter-American Observatory ....................................................... 11 3.2 Kitt Peak National Observatory ....................................................................... 14 3.3 Gemini Observatory ........................................................................................
    [Show full text]
  • Arxiv:Astro-Ph/0507464V2 14 Jan 2009 Eso H Ai Fitgae A-Vpooer.The Photometry
    Astrophysics and Space Science DOI 10.1007/s•••••-•••-••••-• Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy M. Catelan1,2 c Springer-Verlag •••• Abstract We review and discuss horizontal branch importance of bright type II Cepheids as tracers of (HB) stars in a broad astrophysical context, includ- faint blue HB stars in distant systems is also empha- ing both variable and non-variable stars. A reassess- sized. The relationship between the absolute V mag- ment of the Oosterhoff dichotomy is presented, which nitude of the HB at the RR Lyrae level and metallic- provides unprecedented detail regarding its origin and ity, as obtained on the basis of trigonometric parallax systematics. We show that the Oosterhoff dichotomy measurements for the star RR Lyr, is also revisited. and the distribution of globular clusters in the HB Taking into due account the evolutionary status of RR morphology-metallicity plane both exclude, with high Lyr, the derived relation implies a true distance mod- statistical significance, the possibility that the Galac- ulus to the LMC of (m−M)0 = 18.44 ± 0.11. Tech- tic halo may have formed from the accretion of dwarf niques providing discrepant slopes and zero points for galaxies resembling present-day Milky Way satellites the MV (RRL) − [Fe/H] relation are briefly discussed. such as Fornax, Sagittarius, and the LMC—an argu- We provide a convenient analytical fit to theoretical ment which, due to its strong reliance on the ancient model predictions for the period change rates of RR RR Lyrae stars, is essentially independent of the chem- Lyrae stars in globular clusters, and compare the model ical evolution of these systems after the very earli- results with the available data.
    [Show full text]
  • Central Kinematics of the Globular Cluster NGC 2808: Upper Limit on the Mass of an Intermediate-Mass Black Hole,
    A&A 542, A129 (2012) Astronomy DOI: 10.1051/0004-6361/201219375 & c ESO 2012 Astrophysics Central kinematics of the globular cluster NGC 2808: upper limit on the mass of an intermediate-mass black hole, N. Lützgendorf1, M. Kissler-Patig1,K.Gebhardt2,H.Baumgardt3, E. Noyola4,5, B. Jalali6, P. T. de Zeeuw1,7, and N. Neumayer1 1 European Southern Observatory (ESO), Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany e-mail: [email protected] 2 Astronomy Department, University of Texas at Austin, Austin, TX 78712, USA 3 School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia 4 Instituto de Astronomia, Universidad Nacional Autonoma de Mexico (UNAM), AP 70-264, 04510 Mexico 5 University Observatory, Ludwig Maximilians University, 81679 Munich, Germany 6 I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany 7 Sterrewacht Leiden, Leiden University, Postbus 9513, 2300 RA Leiden, The Netherlands Received 10 April 2012 / Accepted 18 April 2012 ABSTRACT Context. Globular clusters are an excellent laboratory for stellar population and dynamical research. Recent studies have shown that these stellar systems are not as simple as previously assumed. With multiple stellar populations as well as outer rotation and mass segregation they turn out to exhibit high complexity. This includes intermediate-mass black holes (IMBHs) which are proposed to sit at the centers of some massive globular clusters. Today’s high angular resolution ground based spectrographs allow velocity-dispersion measurements at a spatial resolution comparable to the radius of influence for plausible IMBH masses, and to detect changes in the inner velocity-dispersion profile.
    [Show full text]
  • Curriculum Vitæ: Manuela Zoccali Associate Professor, Puc
    CURRICULUM VITÆ: MANUELA ZOCCALI ASSOCIATE PROFESSOR, PUC PERSONAL INFORMATION Name: Manuela Surname: Zoccali Birth place: Reggio Calabria, Italy Birth date: September 11th, 1971 Citizenship: Italian Current Position: Profesor Asociado Departamento de Astronomía y Astrofísica P. Universidad Católica de Chile Av. Vicuña Mackenna 4860, 782-0436, Macul, Santiago, Chile Telephone: +56-2-354-7253 Fax: +56-2-354-4948 e-mail: [email protected] SPOKEN LANGUAGES Italian: mother tongue English: fluent Spanish: fluent French: basic EDUCATIONAL BACKGROUND 1995 — Laurea (Bachelor) Degree in Astronomy , Università di Padova, Italy (Magna cum Laude) Thesis title: Funzione di luminosità e di massa dell'ammasso globulare galattico NGC1261. Advisors: Prof. M. Capaccioli, Prof. G. Piotto 2000 — PhD in Astronomy, Università di Padova, Italy (no marks for Phd, in Italy) Thesis title: Observational Constraints on the Evolutionary and Dynamical Properties of Low Mass Stars. Advisor: Prof. G. Piotto EMPLOYMENT HISTORY 2000 – 2003 Post-doctoral Fellowship at the European Southern Observatory (ESO), Garching bei München, Germany 2003 – 2004 Post-doctoral Princeton-PUC Prize Fellowship between the University of Princeton (NJ, USA) and the P. Univ. Católica de Chile. 2004 – 2008 Assistant Professor, P. Universidad Católica de Chile. 2008 – Present Associate Professor, P. Universidad Católica de Chile. PRIMARY RESEARCH INTERESTS Stellar Populations, Globular Star Clusters, The Galactic Bulge, Stellar Abundances, The Initial Mass Function, Galaxy Formation and Evolution. TEACHING 2004 – 2009 Teaching of Astronomy courses for Astronomy students at the undergraduate (Astronomy, Astronomy Lab I and II, Galactic Astronomy) and graduate levels (Topics in Astrophysics, Galaxy Formation). Physics courses for undergraduate Engineering students (Classical Mechanics). 2005 – 2009 Advisor of 2 PhD (F.
    [Show full text]
  • Testing Metal Poor Stellar Models and Isochrones with Hst Parallaxes of Metal Poor Stars
    Draft version November 11, 2018 Preprint typeset using LATEX style AASTeX6 v. 1.0 TESTING METAL POOR STELLAR MODELS AND ISOCHRONES WITH HST PARALLAXES OF METAL POOR STARS B. Chaboyer1,2, B.E. McArthur3, E. O'Malley1, G.F. Benedict3, G. A.Feiden4, T.E. Harrison5, A. McWilliam6, E.P. Nelan7, R.J. Patterson8, A. Sarajedini9 1Dept. of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 USA 2Max-Planck-Institut f¨urAstrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching bei M¨unchen, Germany 3McDonald Observatory, University of Texas, Austin, TX 78712 USA 4Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20, Uppsala, Sweden 5Dept. of Astronomy, New Mexico State University, Las Cruces, NM 88003 USA 6The Observatories of the Carnegie Institute of Washington, Pasadena, CA 91101 USA 7Space Telescope Science Institute, Baltimore, MD 21218 USA 8Dept. of Astronomy, University of Virginia, Charlottesville, VA 22904 USA 9Dept. of Astronomy, University of Florida, Gainesville, FL 32611 USA ABSTRACT Hubble Space Telescope (HST) fine guidance sensor observations were used to obtain parallaxes of eight metal-poor ([Fe=H] < −1:4) stars. The parallaxes of these stars determined by the new Hipparcos reduction average 17% accuracy, in contrast to our new HST parallaxes which average 1% accuracy and have errors on the individual parallaxes ranging from 85 to 144 microarcseconds. This parallax data has been combined with HST ACS photometry in the F606W and F814W filters to obtain the absolute magnitudes of the stars with an accuracy of 0.02 to 0.03 magnitudes. Six of these stars are on the main sequence (with −2:7 < [Fe=H] < −1:8), and suitable for testing metal-poor stellar evolution models and determining the distances to metal-poor globular clusters.
    [Show full text]
  • SOAR Publications Sorted by Year Then Author (Last Updated November 24, 2016 by Nicole Auza)
    No longer maintained, see home page for current information! SOAR publications Sorted by year then author (Last updated November 24, 2016 by Nicole Auza) ⇒If your publication(s) are not listed in this document, please fill in this form to enable us to keep a complete list of SOAR publications. Contents 1 Refereed papers 1 2 Conference proceedings 35 3 SPIE Conference Series 39 4 PhD theses 46 5 Meeting (incl. AAS) abstracts 47 6 Circulars 55 7 ArXiv 60 8 Other 61 1 Refereed papers (2016,2015, 2014, 2013, 2012, 2011, 2010, 2009, 2008, 2007, 2006, 2005) 2016 [1] Alvarez-Candal, A., Pinilla-Alonso, N., Ortiz, J. L., Duffard, R., Morales, N., Santos- Sanz, P., Thirouin, A., & Silva, J. S. 2016 Feb, Absolute magnitudes and phase coefficients of trans-Neptunian objects, A&A, 586, A155 URL http://adsabs.harvard.edu/abs/2016A%26A...586A.155A [2] A´lvarez Crespo, N., Masetti, N., Ricci, F., Landoni, M., Pati˜no-Alvarez,´ V., Mas- saro, F., D’Abrusco, R., Paggi, A., Chavushyan, V., Jim´enez-Bail´on, E., Torrealba, J., Latronico, L., La Franca, F., Smith, H. A., & Tosti, G. 2016 Feb, Optical Spectro- scopic Observations of Gamma-ray Blazar Candidates. V. TNG, KPNO, and OAN Observations of Blazar Candidates of Uncertain Type in the Northern Hemisphere, AJ, 151, 32 URL http://adsabs.harvard.edu/abs/2016AJ....151...32A [3] A´lvarez Crespo, N., Massaro, F., Milisavljevic, D., Landoni, M., Chavushyan, V., Pati˜no-Alvarez,´ V., Masetti, N., Jim´enez-Bail´on, E., Strader, J., Chomiuk, L., Kata- giri, H., Kagaya, M., Cheung, C.
    [Show full text]
  • Summary of Eighth Meeting on Hot Subdwarfs and Related Objects
    Open Astron. 2017; 26: 120–133 Review Article Anthony Eugene Lynas-Gray* Summary of Eighth Meeting on Hot Subdwarfs and Related Objects https://doi.org/10.1515/astro-2017-0429 Received Sep 30, 2017; accepted Dec 15, 2017 Abstract: Subjects discussed during the Eighth Meeting on Hot Subdwarfs and Related Objects are summarised. In par- ticular, a succinct presentation is given of challenges to stellar evolution arising from recent observations. Mention is also made of topics not covered in the meeting such as the need for small revisions to stellar envelope opacities currently in use. I conclude with a brief discussion of current developments which will influence future hot subdwarf research and necessary initiatives that need to be taken. Keywords: stars: subdwarfs, stars: evolution, stars: chemically peculiar 1 Subjects Discussed bility are given by Ge et al. (2010, 2015) while Pavlovskii & Ivanova (2015) and Pavlovskii et al. (2017) model the asymptotic response of donor stars in interacting binary Heber (2009, 2016) and Lynas-Gray (2004) review the de- systems to very rapid mass-loss, characterised by adia- velopment of hot subdwarf research. For more detailed batic expansion throughout their interiors. Han’s conclu- summaries of early work, see Zwicky (1965a,b) and Green- sions were: a) the Roche model may be invalid for extreme stein (1987). Much of the work discussed during the Eighth mass ratios, b) Roche lobe overflow (RLOF) may be more Meeting on Hot Subdwarfs and Related Objects (hereafter stable than previously supposed and c) Common Envelope sdOB8) reflects advances made since Heber (2016) submit- (CE) ejection may be more efficient for red giant – Main ted his review for publication.
    [Show full text]