Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.14/133009
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- Title
- Origins of the thick disk as traced by the alpha elements of metal-poor giant stars selected from RAVE
- Related
- Astrophysical journal. Letters, Vol. 721, No. 2, (2010), p.L92-L96
- DOI
- 10.1088/2041-8205/721/2/L92
- Publisher
- Institute of Physics
- Date
- 2010
- FoR/RFCD Code(s)
-
020100 Astronomical and Space Sciences
- Author/Creator
- Ruchti, G. R
- Author/Creator
- Fulbright, J. P
- Author/Creator
- Grebel, E. K
- Author/Creator
- Helmi, A
- Author/Creator
- Munari, U
- Author/Creator
- Navarro, J. F
- Author/Creator
- Parker, Q. A
- Author/Creator
- Reid, W
- Author/Creator
- Seabroke, G. M
- Author/Creator
- Siebert, A
- Author/Creator
- Siviero, A
- Author/Creator
- Steinmetz, M
- Author/Creator
- Wyse, R. F. G
- Author/Creator
- Watson, F. G
- Author/Creator
- Williams, M
- Author/Creator
- Zwitter, T
- Author/Creator
- Gilmore, G. F
- Author/Creator
- Bienaymé, O
- Author/Creator
- Binney, J
- Author/Creator
- Bland-Hawthorn, J
- Author/Creator
- Campbell, R
- Author/Creator
- Freeman, K. C
- Author/Creator
- Gibson, B. K
- Description
- 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] ≲ –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.
- Description
- 5 page(s)
- Subject Keyword
- 020100 Astronomical and Space Sciences
- Subject Keyword
- galaxy: abundances
- Subject Keyword
- galaxy: disk
- Subject Keyword
- stars: abundances
- Subject Keyword
- stars: late-type
- Resource Type
- journal article
- Organisation
- Macquarie University. Dept. of Physics and Astronomy
- Identifier
- http://hdl.handle.net/1959.14/133009
- Identifier
- ISSN:2041-8205
- Identifier
- mq-rm-2010001994
- Language
- eng
- Reviewed
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