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dc.contributor.authorBell, Eric F.
dc.contributor.authorXue, Xiang Xiang
dc.contributor.authorRix, Hans-Walter
dc.contributor.authorRuhland, Christine
dc.contributor.authorHogg, David W.
dc.date.accessioned2011-12-21T09:01:11Z
dc.date.available2011-12-21T09:01:11Z
dc.date.issued2010-12
dc.identifier.citationBell , E F , Xue , X X , Rix , H-W , Ruhland , C & Hogg , D W 2010 , ' Stellar population variations in the Milky Way's stellar halo ' , The Astronomical Journal , vol. 140 , no. 6 , pp. 1850-1859 . https://doi.org/10.1088/0004-6256/140/6/1850
dc.identifier.issn0004-6256
dc.identifier.otherPURE: 493629
dc.identifier.otherPURE UUID: f2b07c41-3c2e-47c7-932f-60e0bf5c73f3
dc.identifier.otherWOS: 000284143500020
dc.identifier.otherScopus: 78649883657
dc.identifier.urihttp://hdl.handle.net/2299/7438
dc.description.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.en
dc.format.extent10
dc.language.isoeng
dc.relation.ispartofThe Astronomical Journal
dc.rightsOpen
dc.subjectgalaxies: bulges
dc.subjectgalaxies: evolution
dc.subjectgalaxies: general
dc.subjectgalaxies: spiral
dc.subjectgalaxies: stellar content
dc.subjectDIGITAL SKY SURVEY
dc.subjectHORIZONTAL-BRANCH STARS
dc.subjectSAGITTARIUS DWARF GALAXY
dc.subjectCOLD DARK-MATTER
dc.subjectA-TYPE STARS
dc.subjectGALACTIC HALO
dc.subjectBLUE STRAGGLERS
dc.subjectTIDAL STREAM
dc.subjectGLOBULAR-CLUSTERS
dc.subjectSPHEROIDAL GALAXY
dc.titleStellar population variations in the Milky Way's stellar haloen
dc.contributor.institutionSchool of Physics, Astronomy and Mathematics
dc.contributor.institutionScience & Technology Research Institute
dc.contributor.institutionCentre for Astrophysics Research
dc.description.statusPeer reviewed
dc.relation.schoolSchool of Physics, Astronomy and Mathematics
dc.description.versiontypeSubmitted Version
dcterms.dateAccepted2010-12
rioxxterms.versionSMUR
rioxxterms.versionofrecordhttps://doi.org/10.1088/0004-6256/140/6/1850
rioxxterms.typeJournal Article/Review
herts.preservation.rarelyaccessedtrue
herts.rights.accesstypeOpen


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