J/A+A/690/A166      Legacy Survey BHB stars                     (Amarante+ 2024)
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Mapping the anisotropic Galactic stellar halo with blue horizontal branch stars.
    Amarante J.A.S., Koposov S.E., Laporte C.F.P.
    <Astron. Astrophys. 690, A166 (2024)>
    =2024A&A...690A.166A        (SIMBAD/NED BibCode)
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ADC_Keywords: Stars, blue ; Stars, horizontal branch ; Photometry, SDSS
Keywords: techniques: photometric - stars: horizontal-branch - Galaxy: halo -
          Galaxy: stellar content - Galaxy: structure

Abstract:
    We used Legacy Survey photometric data to probe the stellar halo in
    multiple directions of the sky using a probabilistic methodology to
    identify Blue Horizontal Branch (BHB) stars. The measured average
    radial density profile follows a double power law in the range
    5<r_gc_/kpc<120, with a density break at r_gc_=~20kpc. This description,
    however, falls short, depending on the chosen line-of-sight, with some
    regions showing no signature of a break in the profile and a wide
    range of density slopes, e.g. outer slope -5.5<~{alpha}_out_<~-4,
    pointing towards a highly anisotropic stellar halo. This explains in
    part the wide range of density profiles reported in the literature
    owing to different tracers and sky coverage. Using our detailed 3-D
    stellar halo density map, we quantify the shape of the Pisces
    overdensity associated with the transient wake response of the
    Galaxy's (dark) halo to the Large Magellanic Cloud (LMC). Measured
    in the LMC's coordinate system, Pisces stands above the background,
    is 60 degrees long and 25 degrees wide and aligned with the LMC's
    orbit. This would correspond to a wake width of ~32kpc at ~70kpc. We
    do not find a statistically significant signature of the collective
    response in density as previously reported in the literature measured
    with K giant stars, despite our larger numbers. We release the
    catalogue constructed in this study with 95446 possible BHB stars and
    their BHB probability.

Description:
    We use objects from Legacy Survey Data Release 9 (Dey et. al.,
    2019AJ....157..168D. to construct a catalogue with 95446 blue
    horizontal branch star candidates.

    We then construct a catalogue with 95446 objects containing LSDR9
    release, brickid and objid. These three parameters provide a unique
    identifier hash.

    The catalogue also includes "R.A.", "Dec.", the extinction corrected
    "g0", "r0", "z0", photometric bands, the colour "grz", the absolute
    "Mg" magnitude, and the probability of a stellar object being a BHB
    star, "PBHB".

File Summary:
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 FileName    Lrecl  Records   Explanations
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ReadMe          80        .   This file
catalog.dat    114    95446   Catalog of blue horizontal branch star candidates
                               (table C1)
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Byte-by-byte Description of file: catalog.dat
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   Bytes Format Units  Label    Explanations
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   1-  4  I4    ---    Release  LSDR9 releaese
   6- 11  I6    ---    Brickid  brickid
  13- 17  I5    ---    Objid    objid
  19- 30  F12.8 deg    RAdeg    Right ascension (J2000)
  32- 43  F12.8 deg    DEdeg    Declination (J2000)
  45- 55  F11.8 mag    g0mag    Extinction corrected g magnitude
  57- 67  F11.8 mag    r0mag    Extinction corrected r magnitude
  69- 79  F11.8 mag    z0mag    Extinction corrected z magnitude
  81- 91  E11.3 mag    grz      grz colour (1)
  93-102  F10.8 mag    gMAG     Absolute g magnitude
 105-114  E10.5 ---    PBHB     Probability of a stellar object being a BHB star
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Note (1): grz colour defined as
 grz = 1.07163(g-r)^5^ - 1.42272(g-r)^4^ + 0.69476(g-r)^3^ - 0.12911(g-r)^2^
        + 0.66993(g-r) - 0.11368 - (r-z)
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Acknowledgements:
    Joao A.S. Amarante, joaoant(at)gmail.com

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(End)                                        Patricia Vannier [CDS]  01-Jul-2024