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Mega (metal-poor) not so much : Non-LTE spectroscopic stellar parameters and abundance determination of Ultra metal-poor stars

Published online by Cambridge University Press:  02 August 2018

Rana Ezzeddine Open the ORCID record for Rana Ezzeddine [Opens in a new window] ,
Tatyana Sitnova ,
Anna Frebel ,
Lyudmilla Mashonkina  and
Bertrand Plez
Rana Ezzeddine
Affiliation:
Joint Institute for Nuclear Astrophysics, Center for the Evolution of the Elements, East Lansing, MI 48824, USA. email: ranae@mit.edu Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
Tatyana Sitnova
Affiliation:
Institute of Astronomy, Russian academy of Sciences, Pyatniskaya 48, 119017, Moscow, Russia
Anna Frebel
Affiliation:
Joint Institute for Nuclear Astrophysics, Center for the Evolution of the Elements, East Lansing, MI 48824, USA. email: ranae@mit.edu Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
Lyudmilla Mashonkina
Affiliation:
Institute of Astronomy, Russian academy of Sciences, Pyatniskaya 48, 119017, Moscow, Russia
Bertrand Plez
Affiliation:
Laboratoire Univers et Particules de Montpellier, Université de Montpellier, CNRS, UMR 5299, Montpellier, France
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Abstract

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We present Non-Local Thermodynamic Equilibrium (Non-LTE) abundance corrections for Mg, Ca, and Fe in 12 ultra metal-poor (UMP) stars ([Fe/H] < −4.00). We show that they increase in absolute value toward the lower metallicity up to 0.45 dex for Mg, 0.30 dex for Ca, and 1.00 dex for Fe. This represents a first step toward a full Non-LTE analysis of chemical species in the UMP stars that will enable us to put useful constraints on the properties of the “First” stars.

Keywords

line: formationstars: abundancesstars: atmospheresstars: fundamental parametersstars: Population II
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 13 , Symposium S334: Rediscovering our Galaxy , July 2017 , pp. 259 - 262
Copyright
Copyright © International Astronomical Union 2018 

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