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The Search for Extremely Low-Metallicity Stars in Dwarf Galaxies Using theNIR Ca II Triplet

Published online by Cambridge University Press:  11 July 2011

M. Koleva ,
Ph. Prugniel ,
I. Vauglin ,
E. Starkenburg ,
V. Hill ,
E. Tolstoy ,
J. I. González Hernández ,
M. Irwin ,
A. Helmi  and
L. Boschman
...Show all authors
E. Starkenburg
Affiliation:
Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands
V. Hill
Affiliation:
Laboratoire Cassiopée UMR 6202, Université de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d’Azur, France
E. Tolstoy
Affiliation:
Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands
J. I. González Hernández
Affiliation:
Dpto. de Astrofísica y Ciencias de la Atmósfera, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
M. Irwin
Affiliation:
Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB03 0HA, UK
A. Helmi
Affiliation:
Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands
L. Boschman
Affiliation:
Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands
P. Francois
Affiliation:
GEPI, Observatoire de Paris-Meudon, CNRS, Univ. de Paris Diderot, Place Jules Janssen, 92190 Meudon, France
G. Battaglia
Affiliation:
European Organization for Astronomical Research in the Southern Hemisphere, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany
P. Jablonka
Affiliation:
Observatoire de Genève, Laboratoire d’Astrophysique de l’École Polytechnique Fédérale de Lausanne (EPFL), 1290 Sauverny, Switzerland
M. Tafelmeyer
Affiliation:
Observatoire de Genève, Laboratoire d’Astrophysique de l’École Polytechnique Fédérale de Lausanne (EPFL), 1290 Sauverny, Switzerland
M. Shetrone
Affiliation:
University of Texas, McDonald Observatory, HC75 Box 1337-McD, Fort Davis, TX 79734, USA
K. Venn
Affiliation:
Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, BC, V8P 1A1, Canada
T. de Boer
Affiliation:
Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands
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Abstract

The NIR Ca II triplet has proven to be an important tool for quantitative spectroscopy. Here we present results of synthetic spectral analysis for the Ca II triplet for low-metallicity red giant stars, combined with observational data. Our results start to deviate strongly from the widely-used and linear empirical calibrations below [Fe/H] = −2. We provide a new calibration for Ca II triplet studies which is valid down until [Fe/H] = −4 and apply this new calibration to current data sets. We suggest that the classical dwarf galaxies are not so devoid of extremely low-metallicity stars as was previously thought and discuss preliminary results and possibilities for follow-up observations of these extremely low-metallicity candidates.

Type
Research Article
Information
European Astronomical Society Publications Series , Volume 48: CRAL-2010 A Universe of Dwarf Galaxies , 2011 , pp. 13 - 18
Copyright
© EAS, EDP Sciences, 2011

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