Related papers: Probing the core and envelope structure of DBV whi…

We present a new method that investigates the evolutionary history of the pulsating DB white dwarf GD358 using asteroseismology. This is done considering the internal C/O profile, which describes the relative abundances of carbon and oxygen…

A detailed record of the physical processes that operate during post-main-sequence evolution is contained in the internal chemical structure of white dwarfs. Global pulsations allow us to probe the stellar interior through asteroseismology,…

The helium-atmosphere (DB) white dwarfs are commonly thought to be the descendants of the hotter PG1159 stars, which initially have uniform He/C/O atmospheres. In this evolutionary scenario, diffusion builds a pure He surface layer which…

White dwarf asteroseismology offers the opportunity to probe the structure and composition of stellar objects governed by relatively simple physical principles. The observational requirements of asteroseismology have been addressed by the…

We study the structure and evolution of white dwarf stars with helium-rich atmospheres (DB) in a self-consistent way with the predictions of time-dependent element diffusion. Our treatment of diffusion includes gravitational settling and…

We consider envelopes of DB white dwarfs which are not composed of pure 4-He, but rather a mixture of 3-He and 4-He. Given this assumption, the same diffusive processes which produce a relatively pure H layer overlying a He layer in the…

Seismological observations with the Whole Earth Telescope (WET) allow the determination of the subsurface compositional structure of white dwarf stars. The hot DO PG 1159 has a helium surface layer with a mass of 0.001 Msun, while the…

The helium-atmosphere (DB) white dwarfs are commonly thought to be the descendants of the hotter PG 1159 stars, which initially have uniform He/C/O atmospheres. In this evolutionary scenario, diffusion builds a pure He surface layer which…

In this paper, we present a model for the long-term evolution of the merger of two unequal mass C/O white dwarfs (WDs). After the dynamical phase of the merger, magnetic stresses rapidly redistribute angular momentum, leading to nearly…

We present follow-up spectroscopy and a detailed model atmosphere analysis of 29 wide double white dwarfs, including eight systems with a crystallized C/O core member. We use state-of-the-art evolutionary models to constrain the physical…

Pulsating white dwarfs provide constraints to the evolution of progenitor stars. We revise He-burning stellar models, with particular attention to core convection and to its connection with the nuclear reactions powering energy generation…

Irradiated brown dwarfs (BDs) provide natural laboratories to test our understanding of substellar and irradiated atmospheres. A handful of short-period BDs around white dwarfs (WDs) have been observed, but the uniquely intense UV-dominated…

Convective driving, the mechanism originally proposed by Brickhill (1991, 1983) for pulsating white dwarf stars, has gained general acceptance as the generic linear instability mechanism in DAV and DBV white dwarfs. This physical mechanism…

We present an asteroseismic analysis of the helium atmosphere white dwarf (a DBV) recently found in the field of view of the Kepler satellite. We analyze the 5-mode pulsation spectrum that was produced based on one month of high cadence…

Hot DQ white dwarfs constitute a new class of white dwarf stars, uncovered recently within the framework of the SDSS project. Recently, three hot DQ white dwarfs have been reported to exhibit photometric variability with periods compatible…

The white dwarfs are promising laboratories for the study of cosmochronology and stellar evolution. Through observations of the pulsating white dwarfs, we can measure their internal structures and compositions, critical to understanding…

Taking advantage of the Gaia Data Release 2, recent studies have revisited the evolution of carbon-polluted white dwarfs (DQs) across a large range of effective temperatures. These analyses have clearly confirmed the existence of two…

We report on the analysis of 34 years of photometric observations of the pulsating helium atmosphere white dwarf GD358. The complete data set includes archival data from 1982-2006, and 1195.2 hours of new observations from 2007- 2016. From…

We investigate the formation of the ten double-lined double white dwarfs that have been observed so far. A detailed stellar evolution code is used to calculate grids of single-star and binary models and we use these to reconstruct possible…

A critical relation in the study of neutron star cooling is the one between surface temperature and interior temperature. This relation is determined by the composition of the neutron star envelope and can be affected by the process of…