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Distant field BHB stars and the mass of the Galaxy II: Photometry and spectroscopy of UKST candidates 16
- Publication Year :
- 2004
- Publisher :
- arXiv, 2004.
-
Abstract
- This is the second in a series of papers presenting a new calculation of the mass of the Galaxy based on radial velocities and distances for a sample of faint 16 < B < 21.3 field blue horizontal-branch (BHB) stars. We present accurate BV CCD photometry and spectra for 142 candidate A-type stars selected from ub_jr photometry of UK Schmidt telescope plates in six high-Galactic-latitude fields. Classification of these candidates produces a sample of 60 BHB stars at distances of 11-52 kpc from the Sun (mean 28 kpc), with heliocentric line-of-sight velocities accurate to 15 km/s, and distance errors < 10%. We provide a summary table listing coordinates and velocities of these stars. The measured dispersion of the radial component of the Galactocentric velocity for this sample is 108+-10 km/s, in agreement with a recent study of the distant halo by Sirko and coworkers. Measurements of the Ca II K line indicate that nearly all the stars are metal-poor with a mean [Fe/H] = -1.8 with dispersion 0.5. Subsequent papers will describe a second survey of BHBs to heliocentric distances 70 < R < 125 kpc and present a new estimate of the mass of the Galaxy.<br />16 pages, 15 figures. Accepted for publication in MNRAS
Details
- Database :
- OpenAIRE
- Accession number :
- edsair.doi...........b02b7bde79d88bdef8d83f4fd7169e21
- Full Text :
- https://doi.org/10.48550/arxiv.astro-ph/0404322