Related papers: Slowly cooling white dwarfs in M13 from stable hyd…
Recently, a new class of white dwarfs (``slowly cooling WDs'') has been identified in the globular cluster M13. The cooling time of these stars is increased by stable thermonuclear hydrogen burning in their residual envelope. These WDs are…
Recently, a new class of white dwarfs (dubbed ``slowly cooling WDs'') has been identified in two globular clusters (namely M13 and NGC 6752) showing a horizontal branch (HB) morphology with an extended blue tail. The cooling rate of these…
Using WFPC2 on the Hubble Space Telescope, we have isolated a sample of 258 white dwarfs (WDs) in the Galactic globular cluster M4. Fields at three radial distances from the cluster center were observed and sizeable WD populations were…
A deep imaging survey covering the entire $23\arcmin$ diameter of the old open cluster M67 to $V = 25$ has been carried out using the mosaic imager (UHCam) on the Canada-France-Hawaii Telescope. The cluster color-magnitude diagram (CMD) can…
White dwarfs are the final remnants of low- and intermediate-mass stars. Their evolution is essentially a cooling process that lasts for $\sim 10$ Gyr. Their observed properties provide information about the history of the Galaxy, its dark…
All single stars that are born with masses up to 8.5 - 10 $M_\odot$ will end their lives as a white dwarf (WD) star. In this evolutionary stage, WDs enter the cooling sequence, where the stars radiate away their thermal energy, and are…
The evolution of white dwarfs is a simple gravothermal process. This means that their luminosity function, i.e. the number of white dwarfs per unit bolometric magnitude and unit volume as a function of bolometric magnitude, is a…
White dwarf (WD) stars are considered cosmic laboratories to study the physics of dense plasma. Furthermore, the use of WD stars as cosmic clocks to date stellar populations and main sequence companions demands an appropriate understanding…
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…
We study the white dwarf (WD) cooling sequence of the Galactic Globular Cluster (GGC) NGC 2808 by using deep near-UV data from the Hubble Space Telescope and theoretical models, to investigate if this cluster hosts an excess of WDs. Excess…
White dwarfs are stellar embers depleted of nuclear energy sources that cool over billions of years. These stars, which are supported by electron degeneracy pressure, reach densities of 1e7 grams per cubic centimetre in their cores. It has…
Recently, the power of Gaia data has revealed an enhancement of high-mass white dwarfs (WDs) on the Hertzsprung--Russell diagram, called the Q branch. This branch is located at the high-mass end of the recently identified crystallization…
Cooling white dwarfs (WDs) can yield accurate ages when theoretical cooling models fully account for the physics of the dense plasma of WD interiors. We use MESA to investigate cooling models for a set of massive and ultra-massive WDs…
We present detailed evolutionary calculations for carbon - oxygen - and helium - core white dwarf (WD) models with masses ranging from M= 0.1 to M= 1.2 solar masses and for metallicities Z= 0.001 and Z= 0. The sequences cover a wide range…
A detailed analysis of halo white dwarf candidates is presented, which is based on model atmosphere fits to observed energy distributions built from photoelectric or photographic magnitudes. Most of the candidates identified in reduced…
White dwarf (WD) stars evolve simply and predictably, making them reliable age indicators. However, self-consistent validation of the methods for determining WD total ages has yet to be widely performed. This work uses 1565 wide ( > 100 au)…
Deriving precise stellar ages is a challenging task. Consequently, age-dependent relations - such as the age-metallicity and age-velocity dispersion relations of the Milky Way, or the age-rotation-activity relation of low-mass stars - are…
White dwarfs are stellar remnants devoid of a nuclear energy source, gradually cooling over billions of years and eventually freezing into a solid state from the inside out. Recently, it was discovered that a population of freezing white…
The present work is designed to explore the evolution of helium-core white dwarf (HeWD) stars for the case of metallicities much lower than the solar one (Z=0.001 and Z=0.0002). Evolution is followed in a self-consistent way with the…
We collected F606W- and F814W-band time-series data of the Sagittarius low-reddening window in the Galactic bulge with the Advanced Camera far Surveys mounted on the Hubble Space Telescope. We sampled the region approximately every two…