Related papers: Understanding the Oldest White Dwarfs: Atmospheres…
Aims: Hydrogen deficient white dwarfs are characterized by very dense, fluid-like atmospheres of complex physics and chemistry that are still poorly understood. The incomplete description of these atmospheres by the models results in…
The evolution of white dwarfs is essentially a cooling process that depends primarily on the energy stored in their degenerate cores and on the transparency of their envelopes. In this paper we compute accurate cooling sequences for…
White Dwarfs (WD) capture Dark Matter (DM) as they orbit within their host halos. These captured particles may subsequently annihilate, heating the stellar core and preventing the WD from cooling. The potential wells of WDs are considerably…
We present optical spectroscopy and near-infrared photometry of 126 cool white dwarfs in the Sloan Digital Sky Survey (SDSS). Our sample includes high proper motion targets selected using the SDSS and USNO-B astrometry and a dozen…
We present theoretical analysis on old white dwarf stars with \emph{some} hydrogen, that possess a mass of surface hydrogen from $1\times10^{-11}M_{\sun}$ to $1\times10^{-7}M_{\sun}$. The evolution of such objects is complicated by…
We present the first grid of 3D simulations for the pure-helium atmospheres of DB white dwarfs. The simulations were computed with the CO5BOLD radiation-hydrodynamics code and cover effective temperatures and surface gravities between 12000…
In our galaxy, the white dwarfs (WDs) will inevitably capture the dark matter (DM) particles streaming through them, if there exist interactions between DM particles and nuclei/electrons. At the same time, these DM particles can also be…
Given the importance of white dwarfs (WDs) in many fields of modern astrophysics, the precise knowledge of the actual degree of accuracy of the associated theoretical predictions is a primary task. In the first paper of a series dedicated…
In the vast expanse of our galaxy, white dwarfs (WDs) are natural sentinels, capturing the enigmatic dark matter (DM) particles that incessantly traverse their interiors. These celestial bodies provide a unique vantage point for probing…
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…
An accurate assessment of white dwarf cooling times is paramount to place white dwarf cosmochronology of Galactic populations on more solid grounds. This issue is particularly relevant in view of the enhanced observational capabilities…
We present an analysis of spectroscopic and photometric observations of cool DQ white dwarfs based on improved model atmosphere calculations. In particular, we revise the atmospheric parameters of the trigonometric parallax sample of…
We briefly examine the properties of dense plasmas characteristic of the atmospheres of neutron stars and of the interior of massive white dwarfs. These astrophysical bodies are natural laboratories to study respectively the problem of…
White dwarfs, the extremely dense remnants left behind by most stars after their death, are characterised by a mass comparable to that of the Sun compressed into the size of an Earth-like planet. In the resulting strong gravity, heavy…
We summarize recent improvements in model atmosphere and internal structure of faint white dwarfs. We derive an analytical cooling theory which illustrates the effects of various physical processes on the energy budget and the cooling…
A large number of extremely low-mass helium white dwarfs (ELM WDs) have been discovered in recent years. The majority of them are found in close binary systems suggesting they are formed either through a common-envelope phase or via stable…
We carried out a spectroscopic investigation of single lined white dwarfs (WDs) in double degenerate (DD) systems and discuss their binary evolution. Simulated spectra of the Halpha region are used to derive upper limits on the temperature…
The shape of the luminosity function of white dwarfs (WDLF) is sensitive to the characteristic cooling time and, therefore, it can be used to test the existence of additional sources or sinks of energy such as those predicted by alternative…
White Dwarf luminosities are powerful age indicators, whose calibration should be based on reliable models. We discuss the uncertainty of some chemical and physical parameters and their influence on the age estimated by means of white dwarf…
With the Cosmic Origins Spectrograph onboard the Hubble Space Telescope, we have detected molecular hydrogen in the atmospheres of three white dwarfs with effective temperatures below 14,000 K, G29-38, GD 133 and GD 31. This discovery…