University of Hertfordshire Research Archive

        JavaScript is disabled for your browser. Some features of this site may not work without it.

        Browse

        All of UHRABy Issue DateAuthorsTitlesThis CollectionBy Issue DateAuthorsTitles

        Arkivum Files

        My Downloads
        View Item 
        • UHRA Home
        • University of Hertfordshire
        • Research publications
        • View Item
        • UHRA Home
        • University of Hertfordshire
        • Research publications
        • View Item

        Stellar population variations in the Milky Way's stellar halo

        View/Open
        ruhland1010.2239v1.pdf (PDF, 620Kb)
        Author
        Bell, Eric F.
        Xue, Xiang Xiang
        Rix, Hans-Walter
        Ruhland, Christine
        Hogg, David W.
        Attention
        2299/7438
        Abstract
        If 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.
        Publication date
        2010-12
        Published in
        The Astronomical Journal
        Published version
        https://doi.org/10.1088/0004-6256/140/6/1850
        Other links
        http://hdl.handle.net/2299/7438
        Metadata
        Show full item record

        Related items

        Showing items related by title, author, creator and subject.

        • The H alpha galaxy survey. I. The galaxy sample, H alpha narrow-band observations and star formation parameters for 334 galaxies 

          James, P.A.; Shane, N.S.; Beckman, J.E.; Cardwell, A.; Collins, C.A.; Etherton, J.; de Jong, R.S.; Fathi, K.; Knapen, J.; Peletier, R.F.; Percival, S.M.; Pollacco, D.L.; Seigar, M.S.; Stedman, S. (2004)
          We discuss the selection and observations of a large sample of nearby galaxies, which we are using to quantify the star formation activity in the local Universe. The sample consists of 334 galaxies across all Hubble types ...
        • On the Key Processes that Drive Galaxy Evolution: the Role of Galaxy Mergers, Accretion, Local Environment and Feedback in Shaping the Present-Day Universe 

          Martin, Garreth (2019-07-17)
          The study of galaxy evolution is a fundamental discipline in modern astrophysics, dealing with how and why galaxies of all types evolve over time. The diversity of present-day galaxies is a reflection of the processes ...
        • Radio Galaxy Zoo: discovery of a poor cluster through a giant wide-angle tail radio galaxy 

          Banfield, J. K.; Andernach, H.; Kapinska, A. D.; Rudnick, L.; Hardcastle, M. J.; Cotter, G.; Vaughan, S.; Jones, T. W.; Heywood, I.; Wing, J. D.; Wong, O. I.; Matorny, T.; Terentev, I. A.; Lopez-Sanchez, A. R.; Norris, R. P.; Seymour, N.; Shabala, S. S.; Willett, K. W. (2016-08-11)
          We have discovered a previously unreported poor cluster of galaxies (RGZ-CL J0823.2+0333) through an unusual giant wide-angle tail radio galaxy found in the Radio Galaxy Zoo project. We obtained a spectroscopic redshift ...
        Keep in touch

        © 2019 University of Hertfordshire

        I want to...

        • Apply for a course
        • Download a Prospectus
        • Find a job at the University
        • Make a complaint
        • Contact the Press Office

        Go to...

        • Accommodation booking
        • Your student record
        • Bayfordbury
        • KASPAR
        • UH Arts

        The small print

        • Terms of use
        • Privacy and cookies
        • Criminal Finances Act 2017
        • Modern Slavery Act 2015
        • Sitemap

        Find/Contact us

        • T: +44 (0)1707 284000
        • E: ask@herts.ac.uk
        • Where to find us
        • Parking
        • hr
        • qaa
        • stonewall
        • AMBA
        • ECU Race Charter
        • disability confident
        • AthenaSwan