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STELLAR POPULATION VARIATIONS IN THE MILKY WAY's STELLAR HALO
Bell, Eric F.1; Xue, Xiang Xiang2,3; Rix, Hans-Walter2; Ruhland, Christine2; Hogg, David W.2,4
2010-12-01
Source PublicationASTRONOMICAL JOURNAL
Volume140Issue:6Pages:1850-1859
AbstractIf the stellar halos of disk galaxies are built up from the disruption of dwarf galaxies, models predict highly structured variations in the stellar populations within these halos. We test this prediction by studying the ratio of blue horizontal branch stars (BHB stars; more abundant in old, metal-poor populations) to main-sequence turn-off stars (MSTO stars; a feature of all populations) in the stellar halo of the Milky Way using data from the Sloan Digital Sky Survey. We develop and apply an improved technique to select BHB stars using ugr color information alone, yielding a sample of similar to 9000 g < 18 candidates where similar to 70% of them are BHB stars. We map the BHB/MSTO ratio across similar to 1/4 of the sky at the distance resolution permitted by the absolute magnitude distribution of MSTO stars. We find large variations of the BHB/MSTO star ratio in the stellar halo. Previously identified, stream-like halo structures have distinctive BHB/MSTO ratios, indicating different ages/metallicities. Some halo features, e. g., the low-latitude structure, appear to be almost completely devoid of BHB stars, whereas other structures appear to be rich in BHB stars. The Sagittarius tidal stream shows an apparent variation in the BHB/MSTO ratio along its extent, which we interpret in terms of population gradients within the progenitor dwarf galaxy. Our detection of coherent stellar population variations between different stellar halo substructures provides yet more support to cosmologically motivated models for stellar halo growth.
KeywordGalaxies: Bulges Galaxies: Evolution Galaxies: General Galaxies: Spiral Galaxies: Stellar Content
DOI10.1088/0004-6256/140/6/1850
Indexed BySCI
Language英语
WOS IDWOS:000284143500020
Citation statistics
Cited Times:44[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Identifierhttp://ir.bao.ac.cn/handle/114a11/7763
Collection星系宇宙学研究部
Affiliation1.Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA
2.Max Planck Inst Astron, D-69117 Heidelberg, Germany
3.CAS, Natl Astron Observ, Key Lab Opt Astron, Beijing 100012, Peoples R China
4.NYU, Dept Phys, Ctr Cosmol & Particle Phys, New York, NY 10003 USA
Recommended Citation
GB/T 7714
Bell, Eric F.,Xue, Xiang Xiang,Rix, Hans-Walter,et al. STELLAR POPULATION VARIATIONS IN THE MILKY WAY's STELLAR HALO[J]. ASTRONOMICAL JOURNAL,2010,140(6):1850-1859.
APA Bell, Eric F.,Xue, Xiang Xiang,Rix, Hans-Walter,Ruhland, Christine,&Hogg, David W..(2010).STELLAR POPULATION VARIATIONS IN THE MILKY WAY's STELLAR HALO.ASTRONOMICAL JOURNAL,140(6),1850-1859.
MLA Bell, Eric F.,et al."STELLAR POPULATION VARIATIONS IN THE MILKY WAY's STELLAR HALO".ASTRONOMICAL JOURNAL 140.6(2010):1850-1859.
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