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High-Resolution Spectra Observed for SPY. II. DB and DBA Stars
B. Voss, D. Koester, R. Napiwotzki +2
We present a detailed spectroscopic analysis of the stars with helium-dominated spectra in the ESO Supernova Ia Progenitor Survey (SPY). Atmospheric parameters, masses, and abundan…
Velocity Fields at the Surface of ZZ Ceti Stars
D. Koester, E. Kompa
We demonstrate that the peculiar line profiles observed in DA white dwarfs in the temperature range of the ZZ Ceti variables can be explained by the surface velocity fields associa…
Do Magnetic Fields Prevent Hydrogen from Accreting onto Cool Metal-line White Dwarf Stars?
S. Friedrich, S. Jordan, D. Koester
It is generally assumed that metals detected in the spectra of a few cool white dwarfs cannot be of primordial origin and must be accreted from the interstellar medium. However, th…
Temperature determination of the cool DO white dwarf HD149499B from EUVE observations
S. Jordan, R. Napiwotzki, D. Koester +1
We present a LTE model atmosphere analysis of the medium and long wavelength spectrum of the cool DO white dwarf HD149499B. This observation in the spectral range 230-700 A supplem…