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Relics of Primordial Star Formation: The Milky Way and Local Dwarfs

Published online by Cambridge University Press:  01 June 2008

Timothy C. Beers ,
Young Sun Lee  and
Daniela Carollo
Timothy C. Beers
Affiliation:
Department of Physics & Astronomy, CSCE: Center for the Study of Cosmic Evolution, and JINA: Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824, USA email: [email protected], [email protected]
Young Sun Lee
Affiliation:
Department of Physics & Astronomy, CSCE: Center for the Study of Cosmic Evolution, and JINA: Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824, USA email: [email protected], [email protected]
Daniela Carollo
Affiliation:
Research School of Astronomy and Astrophysics, Australian National University, Mount Stromlo Observatory, Cotter Road, Weston, ACT 2611, Australia, and INAF-Osservatorio Astronomico di Torino, 10025 Pino Torinese, Italy, email: [email protected]
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Abstract

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Massive spectroscopic surveys of stars in the thick disk and halo populations of the Galaxy hold the potential to provide strong constraints on the processes involved in (and the timing of) the assembly history of the primary structural components of the Galaxy. In this talk, we explore what has been learned from one of the first such dedicated surveys, SDSS/SEGUE. Over the course of the past three years, SEGUE has obtained spectra for over 200,000 stars, while another hundred thousand stars been added from the calibration star observations of the (primarily extragalactic) SDSS, and other directed programs. A total of well over 10,000 stars with [Fe/H] < −2.0 have been discovered, including several hundred with [Fe/H] < −3.0. Their kinematics have revealed a inner/outer halo structure of the Galaxy.

New determinations of the alpha element ratios for tens of thousands of these stars are reported. Correlations of the alpha-element ratios with kinematics and orbital parameters can be used to test models of the likely formation of the thick-disk and halo components. These new data will (eventually) be considered in connection with possible associations with the present dwarf satellite galaxies of the Milky Way.

Keywords

Astronomical data bases: surveystechniques: spectroscopicmethods: data analysisstars: fundamental parametersGalaxy: diskGalaxy: halo
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 4 , Issue S255: Low-Metallicity Star Formation: From the First Stars to Dwarf Galaxies , June 2008 , pp. 323 - 329
Copyright
Copyright © International Astronomical Union 2008

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