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Article: Origins of the thick disk as traced by the alpha elements of metal-poor giant stars selected from RAVE

TitleOrigins of the thick disk as traced by the alpha elements of metal-poor giant stars selected from RAVE
Authors
KeywordsGalaxy: abundances
Stars: late-type
Stars: abundances
Galaxy: disk
Issue Date2010
Citation
Astrophysical Journal Letters, 2010, v. 721, n. 2 PART 2, p. L92-L96 How to Cite?
AbstractTheories 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. © 2010 The American Astronomical Society. All rights reserved.
Persistent Identifierhttp://hdl.handle.net/10722/208914
ISSN
2015 Impact Factor: 5.487
2015 SCImago Journal Rankings: 3.369

 

DC FieldValueLanguage
dc.contributor.authorRuchti, Gregory R.-
dc.contributor.authorFulbright, Jon P.-
dc.contributor.authorWyse, Rosemary F G-
dc.contributor.authorGilmore, Gerard F.-
dc.contributor.authorBienaymé, Olivier-
dc.contributor.authorBinney, James J.-
dc.contributor.authorBland-Hawthorn, Joss Bland-
dc.contributor.authorCampbell, Randy D.-
dc.contributor.authorFreeman, Kenneth C.-
dc.contributor.authorGibson, Brad K.-
dc.contributor.authorGrebel, Eva K.-
dc.contributor.authorHelmi, Amina-
dc.contributor.authorMunari, Ulisse-
dc.contributor.authorNavarro, Julio F.-
dc.contributor.authorParker, Quentin A.-
dc.contributor.authorReid, Warren A.-
dc.contributor.authorSeabroke, George M.-
dc.contributor.authorSiebert, Arnaud-
dc.contributor.authorSiviero, Alessandro-
dc.contributor.authorSteinmetz, Matthias-
dc.contributor.authorWatson, Fred G.-
dc.contributor.authorWilliams, Mary E K-
dc.contributor.authorZwitter, Tomaž-
dc.date.accessioned2015-03-23T02:02:10Z-
dc.date.available2015-03-23T02:02:10Z-
dc.date.issued2010-
dc.identifier.citationAstrophysical Journal Letters, 2010, v. 721, n. 2 PART 2, p. L92-L96-
dc.identifier.issn2041-8205-
dc.identifier.urihttp://hdl.handle.net/10722/208914-
dc.description.abstractTheories 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. © 2010 The American Astronomical Society. All rights reserved.-
dc.languageeng-
dc.relation.ispartofAstrophysical Journal Letters-
dc.subjectGalaxy: abundances-
dc.subjectStars: late-type-
dc.subjectStars: abundances-
dc.subjectGalaxy: disk-
dc.titleOrigins of the thick disk as traced by the alpha elements of metal-poor giant stars selected from RAVE-
dc.typeArticle-
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1088/2041-8205/721/2/L92-
dc.identifier.scopuseid_2-s2.0-78649264102-
dc.identifier.volume721-
dc.identifier.issue2 PART 2-
dc.identifier.spageL92-
dc.identifier.epageL96-
dc.identifier.eissn2041-8213-

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