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The Potential of White Dwarf Cosmochronology
In the light of recent significant progress on both the observational and theoretical fronts, we review the status of white dwarf stars as cosmochronometers. These objects represent the end products
Spectroscopic Studies of DB White Dwarfs: The Instability Strip of the Pulsating DB (V777 Herculis) Stars
We have secured optical spectra for the eight currently known variable DB, or V777 Her, stars. With the help of a new generation of synthetic spectra, spectroscopic effective temperatures are derived
A compact system of small planets around a former red-giant star
The presence of two nearly Earth-sized bodies orbiting the post-red-giant, hot B subdwarf star KIC 05807616 is reported, which may be the dense cores of evaporated giant planets that were transported closer to the star during the engulfment and triggered the mass loss necessary for the formation of the hot B subswarf.
The Pulsating White Dwarf Stars
We present a summary of what is currently known about the three distinct families of isolated pulsating white dwarfs. These are the GW Vir stars (He/C/O-atmosphere stars with Teff 120,000 K), the
We present new cooling sequences, color-magnitude diagrams, and color-color diagrams for cool white dwarfs with pure hydrogen atmospheres down to an effective temperature Teff = 1500 K. We include a
A preliminary look at the empirical mass distribution of hot B subdwarf stars
We present the results of about a decade of efforts toward building an empirical mass distribution for hot B subdwarf stars on the basis of asteroseismology. So far, our group has published detailed
Discovery and Asteroseismological Analysis of the Pulsating sdB Star PG 0014+067*
We report the discovery of low-amplitude, short-period, multiperiodic luminosity variations in the hot B subdwarf PG 0014+067. This star was selected as a potential target in the course of our
The Newly Discovered Pulsating Low-mass White Dwarfs: An Extension of the ZZ Ceti Instability Strip
In light of the exciting discovery of g-mode pulsations in extremely low-mass, He-core DA white dwarfs, we report on the results of a detailed stability survey aimed at explaining the existence of
Adiabatic properties of pulsating DA white dwarfs. IV - an extensive survey of the period structure of evolutionary models
The results of a detailed adiabatic survey of the pulsation properties of evolutionary models of pulsating DA white dwarfs are presented. Pulsation periods, kinetic energies, and first-order rotation
Adiabatic properties of pulsating DA white dwarfs. II: Mode trapping in compositionally stratified models
As part of a series of investigations aimed at understanding the adiabatic gravity-mode period structure of models of pulsating DA white dwarfs, we examine qualitatively and quantitatively the