Abstract
AbstractIn preparation for the upcoming all-sky data releases of the Gaia mission, we compiled a catalog of known hot subdwarf stars and candidates drawn from the literature and yet unpublished databases. The catalog contains 5613 unique sources and provides multi-band photometry from the ultraviolet to the far infrared, ground based proper motions, classifications based on spectroscopy and colors, published atmospheric parameters, radial velocities and light curve variability information. Using several different techniques, we removed outliers and misclassified objects. By matching this catalog with astrometric and photometric data from the Gaia mission, we will develop selection criteria to construct a homogeneous, magnitude-limited all-sky catalog of hot subdwarf stars based on Gaia data. As first application of the catalog data, we present the quantitative spectral analysis of 280 sdB and sdOB stars from the Sloan Digital Sky Survey Data Release 7. Combining our derived parameters with state-of-the-art proper motions, we performed a full kinematic analysis of our sample. This allowed us to separate the first significantly large sample of 78 sdBs and sdOBs belonging to the Galactic halo. Comparing the properties of hot subdwarfs from the disk and the halo with hot subdwarf samples from the globular clusters ω Cen and NGC 2808, we found the fraction of intermediate He-sdOBs in the field halo population to be significantly smaller than in the globular clusters.
Highlights
Hot subdwarf stars have spectra similar to main sequence O/B stars, but are subluminous and more compact
In preparation for the upcoming all-sky data releases of the Gaia mission, we compiled a catalog of known hot subdwarf stars and candidates drawn from the literature and yet unpublished databases
The catalog contains 5613 unique sources and provides multi-band photometry from the ultraviolet to the far infrared, ground based proper motions, classifications based on spectroscopy and colors, published atmospheric parameters, radial velocities and light curve variability information
Summary
Hot subdwarf stars (sdO/Bs) have spectra similar to main sequence O/B stars, but are subluminous and more compact. The Sloan Digital Sky Survey (SDSS) provided spectra of almost 2000 sdO/Bs (Geier et al 2015; Kepler et al 2015, 2016), reaching down to much fainter magnitudes than previous surveys. Catalog of hot subdwarfs the far infrared Given this wealth of new high quality data, we consider it timely to compile a new catalog of hot subdwarf stars (Geier et al 2017). This catalog will be used as input and calibration dataset to select a magnitude-limited, homogeneous, allsky catalog of hot subdwarf stars using astrometry and photometry from the Gaia mission, which will allow us to study the properties of the hot subdwarf population with unprecedented accuracy
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