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A Large-Scale Spectroscopic Survey of Early-Type Stars at High Galactic Latitudes
We present new model atmosphere analyses of optical spectroscopy of alarge sample of B-type stellar candidates. Of a total of 298 objects,the largest sample of its kind to date, 205 were drawn from the PalomarGreen Survey of high Galactic latitude ultraviolet-excess stellarobjects and comprise a complete magnitude-limited sample. Effectivetemperatures, surface gravities, and helium abundances for the hotsubdwarf (high-gravity) component of the sample are derived from adetailed line profile analysis of the hydrogen and helium absorptionlines in intermediate-resolution (3-5 A FWHM) optical spectra. Aseparate analysis of the lower gravity component is made using a newlycalculated grid of synthetic spectra. Additional estimates of theeffective temperatures are made from wide- and intermediate-bandphotometry taken from the literature. We are currently undertaking twofollow-up programs. (1) Detailed abundance analyses of high-resolutionechelle spectra of the lower gravity component of the survey usingmodern model atmosphere and synthetic spectrum techniques willdifferentiate between massive Population I main-sequence B stars andlow-mass, lower luminosity Population II blue horizontal branch starsand post-asymptotic giant branch stars. (2) The derived atmosphericparameters for the higher gravity component, the field extendedhorizontal branch stars, will be combined with radial velocitymeasurements to determine their spatial and kinematic distributions,which will distinguish between competing evolutionary scenarios for thishot, evolved stellar population.
| The Nature of Faint Blue Stars in the Halo. II
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974ApJS...28..157G&db_key=AST
| The Evolutionary Status of the Blue Halo Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973ApJS...26...37N&db_key=AST
| A Photometric Classification of the Feige Blue Stars
Abstract image available at:http://adsabs.harvard.edu/abs/1970PASP...82.1305G
| Mean absolute magnitude of the blue stars at high galactic latitude.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1962AJ.....67..740K&db_key=AST
| An Atlas of Indentification Charts for 113 Blue Stars.
Abstract image available at:http://adsabs.harvard.edu/abs/1959ApJ...129..600F
| A Search for Underluminous Hot Stars.
Abstract image available at:http://adsabs.harvard.edu/abs/1958ApJ...128..267F
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