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J/ApJ/731/119       BHB candidates in Sagittarius stream       (Ruhland+, 2011)

The structure of the Sagittarius stellar stream as traced by blue horizontal branch stars. Ruhland C., Bell E.F., Rix H.-W., Xue X.-X. <Astrophys. J., 731, 119 (2011)> =2011ApJ...731..119R
ADC_Keywords: Stars, horizontal branch ; Radial velocities ; Photometry, SDSS ; Abundances, [Fe/H] Keywords: galaxies: dwarf - galaxies: interactions - Galaxy: halo - Galaxy: stellar content Abstract: We use a sample of blue horizontal branch (BHB) stars from the Sloan Digital Sky Survey Data Release 7 (Cat. II/294) to explore the structure of the tidal tails from the Sagittarius Dwarf Galaxy. We use a method yielding BHB star candidates with up to ∼70% purity from photometry alone. The resulting sample has a distance precision of roughly 5% and can probe distances in excess of 100kpc. Using this sample, we identify a possible extension to the trailing arm at distances of 60-80kpc from the Sun with an estimated significance of at least 3.8σ. Current models predict that a distant "returning" segment of the debris stream should exist, but place it substantially closer to the Sun where no debris is observed in our data. Exploiting the distance precision of our tracers, we estimate the mean line-of-sight thickness of the leading arm to be ∼3kpc, and show that the two "bifurcated" branches of the debris stream differ by only 1-2kpc in distance. With a spectroscopic very pure BHB star subsample, we estimate the velocity dispersion in the leading arm, 37km/s, which is in reasonable agreement with models of Sgr disruption. We finally present a sample of high-probability Sgr BHB stars in the leading arm of Sgr, selected to have distances and velocities consistent with Sgr membership, to allow further study. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table5.dat 94 70 Sample selected for a high probability of association with Sagittarius
See also: II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009) J/A+A/522/A88 : Photometric identification of BHB stars (Smith+, 2010) J/ApJ/684/1143 : BHB candidates in the Milky Way (Xue+, 2008) J/AJ/130/1097 : BHB stars in Century Survey Galactic Halo Project (Brown+, 2005) J/AJ/127/899 : Blue HB stars in SDSS (Sirko+, 2004) J/AJ/128/245 : M giant stars in the Sgr dwarf galaxy (Majewski+, 2004) J/ApJ/588/824 : Velocities of blue stars near (l,b)=(198,-27) (Yanny+, 2003) J/AJ/117/2308 : Spectroscopy of hot stars in the halo (Wilhelm+, 1999) J/AJ/109/1086 : VI Photometry in M54 and Sgr Dwarf Galaxy (Sarajedini+ 1995) J/AJ/108/1722 : Blue horizontal branch stars (Kinman+ 1994) : SDSS home page Byte-by-byte Description of file: table5.dat
Bytes Format Units Label Explanations
1- 10 F10.6 deg RAdeg Right ascension (J2000) 12- 22 F11.8 deg DEdeg Declination (J2000) 24- 32 F9.5 deg GLON Galactic longitude 34- 42 F9.6 deg GLAT Galactic latitude 44- 48 F5.2 mag gmag [17/20] SDSS-DR7 g-band magnitude 50- 53 F4.2 mag u-g u-g color index 55- 59 F5.2 mag g-r g-r color index 61- 64 F4.2 --- Pbhb [0/1] BHB probability 66- 70 F5.1 km/s HRV [-83/74] Heliocentric radial velocity (1) 72- 75 F4.1 km/s e_HRV [3/24] HRV uncertainty 77- 82 F6.1 km/s RVgal [-109/55] Radial velocity in the Galactic standard of rest (1) 84- 88 F5.1 [Sun] Fe/H [-2.4/-1]?=-10 Metallicity 90- 94 F5.1 [Sun] e_Fe/H [0/1.1]?=-10 Fe/H uncertainty
Note (1): Throughout the paper, the radial velocities are given in the Galactic standard of rest, which are the heliocentric radial velocities corrected for the Galactic rotation assuming a rotation velocity of 220km/s for the local standard of rest and (+10.0, +5.2, +7.2) km/s for the solar motion where the directions are defined as pointing toward the Galactic center, in the direction of rotation and toward the north Galactic Pole (see Xue et al. 2008, Cat. J/ApJ/684/1143, for details).
History: From electronic version of the journal
(End) Emmanuelle Perret [CDS] 23-May-2013
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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