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J/A+A/583/A86 DB white dwarfs in SDSS DR10 and DR12 (Koester+, 2015)
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table1.dat
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Beginning of ReadMe :J/A+A/583/A86 DB white dwarfs in SDSS DR10 and DR12 (Koester+, 2015)
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DB white dwarfs in the Sloan Digital Sky Survey Data Release 10 and 12.
Koester D., Kepler S.O.
<Astron. Astrophys. 583, A86 (2015)>
=2015A&A...583A..86K (SIMBAD/NED BibCode)
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ADC_Keywords: Stars, white dwarf ; Abundances
Keywords: white dwarf - stars: atmosphere - stars: abundances - convection -
accretion, accretion disks
Abstract:
White dwarfs with helium-dominated atmospheres (spectral types DO, DB)
comprise approximately 20% of all white dwarfs. There are fewer
studies than of their hydrogen-rich counterparts (DA) and thus several
questions remain open. Among these are the total masses and the origin
of the hydrogen traces observed in a large number and the nature of
the deficit of DBs in the range from 30000-45000K. We use the
largest-ever sample (by a factor of 10) provided by the Sloan Digital
Sky Survey (SDSS) to study these questions.
The photometric and spectroscopic data of 1107 helium-rich objects
from the SDSS are analyzed using theoretical model atmospheres. Along
with the effective temperature and surface gravity, we also determine
hydrogen and calcium abundances or upper limits for all objects. The
atmosphere models are extended with envelope calculations to determine
the extent of the helium convection zones and thus the total amount of
hydrogen and calcium present.
Description:
Stellar parameters for the DB white dwarfs in the SDSS Data Release 10
and 12: effective temperature, surface gravity, signal-to-noise ratio,
distance, distance above galactic plane, logarithmic abundances of H
and Ca. A zero value for the errors means that the surface gravity was
kept fixed at 8.00, or for the abundances that these are upper limits.