Ruchti, GR;
Fulbright, JP;
Wyse, RFG;
Gilmore, GF;
Bienayme, O;
Binney, J;
Bland-Hawthorn, J;
... Zwitter, T; + view all
(2010)
ORIGINS OF THE THICK DISK AS TRACED BY THE ALPHA ELEMENTS OF METAL-POOR GIANT STARS SELECTED FROM RAVE.
The Astrophysical Journal Letters
, 721
(2)
L92-L96.
10.1088/2041-8205/721/2/L92.
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Abstract
Theories of thick-disk formation can be differentiated by measurements of stellar elemental abundances. We have undertaken a study of metal-poor stars selected from the RAVE spectroscopic survey of bright stars to establish whether or not there is a significant population of metal-poor thick-disk stars ([Fe/H] lesssim –1.0) and to measure their elemental abundances. In this Letter, we present abundances of four α-elements (Mg, Si, Ca, and Ti) and iron for a subsample of 212 red giant branch and 31 red clump/horizontal branch stars from this study. We find that the [α/Fe] ratios are enhanced, implying that enrichment proceeded by purely core-collapse supernovae. This requires that star formation in each star-forming region had a short duration. The relative lack of scatter in the [α/Fe] ratios implies good mixing in the interstellar medium prior to star formation. In addition, the ratios resemble that of the halo, indicating that the halo and thick disk share a similar massive star initial mass function. We conclude that the α-enhancement of the metal-poor thick disk implies that direct accretion of stars from dwarf galaxies similar to surviving dwarf galaxies today did not play a major role in the formation of the thick disk.
| Type: | Article |
|---|---|
| Title: | ORIGINS OF THE THICK DISK AS TRACED BY THE ALPHA ELEMENTS OF METAL-POOR GIANT STARS SELECTED FROM RAVE |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1088/2041-8205/721/2/L92 |
| Publisher version: | https://doi.org/10.1088/2041-8205/721/2/L92 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Galaxy: abundances – Galaxy: disk – stars: abundances – stars: late-type |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10090719 |
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