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Hot subdwarf stars in the Galactic halo Tracers of prominent events in late stellar evolution

Published online by Cambridge University Press:  09 May 2016

Stephan Geier ,
Thomas Kupfer ,
Veronika Schaffenroth ,
Ulrich Heber  and
the MUCHFUSS collaboration
Stephan Geier
Affiliation:
European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany Dr. Karl Remeis-Observatory & ECAP, Astronomical Institute, Friedrich-Alexander University Erlangen-Nürnberg, Sternwartstr. 7, D 96049 Bamberg, Germany
Thomas Kupfer
Affiliation:
Department of Astrophysics/IMAPP, Radboud University Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands
Veronika Schaffenroth
Affiliation:
European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany Institute for Astro- and Particle Physics, University of Innsbruck, Technikerstr. 25/8, 6020 Innsbruck, Austria
Ulrich Heber
Affiliation:
Institute for Astro- and Particle Physics, University of Innsbruck, Technikerstr. 25/8, 6020 Innsbruck, Austria
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Abstract

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Hot subdwarf stars (sdO/Bs) are the stripped cores of red giants located at the bluest extension of the horizontal branch. They constitute the dominant population of UV-bright stars in old stellar environments and are most likely formed by binary interactions. We perform the first systematic, spectroscopic analysis of a sample of those stars in the Galactic halo based on data from SDSS. In the course of this project we discovered 177 close binary candidates. A significant fraction of the sdB binaries turned out to have close substellar companions, which shows that brown dwarfs and planets can significantly influence late stellar evolution. Close hot subdwarf binaries with massive white dwarf companions on the other hand are good candidates for the progenitors of type Ia supernovae. We discovered a hypervelocity star, which not only turned out to be the fastest unbound star known in our Galaxy, but also the surviving companion of such a supernova explosion.

Keywords

binaries: spectroscopicbinaries: eclipsingstars: subdwarfsstars: brown dwarfs
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 11 , Issue S317: The General Assembly of Galaxy Halos: Structure, Origin and Evolution , August 2015 , pp. 302 - 303
Copyright
Copyright © International Astronomical Union 2016 

References

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