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Abundance Patterns Among Very Metal-Poor Stars in the Halo of the Galaxy: A Statistical Approach

Published online by Cambridge University Press:  13 April 2010

Vinicius M. Placco ,
Silvia Rossi ,
Timothy C. Beers  and
Sara Lucatello
Vinicius M. Placco
Affiliation:
Departamento de Astronomia - Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, São Paulo, SP 05508-900, Brazil
Silvia Rossi
Affiliation:
Departamento de Astronomia - Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, São Paulo, SP 05508-900, Brazil
Timothy C. Beers
Affiliation:
Department of Physics & Astronomy and JINA: Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824, USA
Sara Lucatello
Affiliation:
Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padua, Italy
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Abstract

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The main goal of this work is to explore the abundance patterns of the very metal-poor stars ([Fe/H]<−2.0) observed by the HERES (Hamburg ESO R-process Enhanced Star - Christlieb et al. 2004) survey. This type of study allows the analysis of the correlations among chemical elements, and place some constraints on the operation of the neutron-capture (r and s) processes in the early Galaxy. This approach makes use of statistical tools, such as agglomerative nesting, which can identify the formation of natural groups based on relations among elemental abundances (e.g. [C/Fe], [Sr/Fe], [Ba/Fe], and [Eu/Fe]), and can also be used in a series of “large-sample like” studies.

This study provides a comprehensive analysis of a sample of 326 metal-poor stars, and introduces two new subclasses (r-0 and s-I) for metal-poor stars with determined abundances of neutron-capture elements, aiming to standardize the nomenclature for those objects and, by reproducing previous results, confirms the validity of the statistical method used.

Keywords

Galaxy: haloGalaxy: stellar contentstars: abundancesmethods: statistical
Type
Poster Papers
Information
Proceedings of the International Astronomical Union , Volume 5 , Symposium S262: Stellar Populations – Planning for the Next Decade , August 2009 , pp. 412 - 413
Copyright
Copyright © International Astronomical Union 2010

References

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Lucatello, S., Beers, T. C., Christlieb, N. et al. 2006, ApJ, 652, L37CrossRefGoogle Scholar