251 datasets found

The existence of ultra-massive white dwarf stars, M_WD_>~1.05M_{sun}, has been reported in several studies. These white dwarfs are relevant for the role they play in type Ia...

We obtained new spectra of fourteen Magellanic Cloud planetary nebulae with the South African Large Telescope to determine heating rates of their central stars and to verify...

Close double degenerate binaries are one of the favoured progenitor channels for type Ia supernovae, but it is unclear how many suitable systems there are in the Galaxy. We...

Among the spectroscopically identified white dwarfs, a fraction smaller than 2% have spectra dominated by carbon lines, mainly molecular C_2_, but also in a smaller group by CI...

Barium (Ba) dwarfs and CH subgiants are the less evolved analogues of Ba and CH giants. They are F- to G-type main-sequence stars polluted with heavy elements by their binary...

Ultra-massive white dwarfs are powerful tools to study various physical processes in the Asymptotic Giant Branch (AGB), type Ia supernova explosions and the theory of...

Line shapes of the magnesium resonance lines in white dwarf spectra are determined by the properties of magnesium atoms and the structure of the white dwarf atmosphere. Through...

Our knowledge of the magnetism in white dwarfs is based on an observational dataset that is biased in favour of stars with very strong magnetic fields. Most of the field...

AR Scorpii is unique amongst known white dwarf binaries in showing powerful pulsations extending to radio frequencies. Here we aim to investigate the multi-frequency radio...

White dwarfs with helium-dominated atmospheres (spectral types DO, DB) comprise approximately 20% of all white dwarfs. There are fewer studies than of their hydrogen-rich...

KUV 05134+2605 is one of the 21 pulsating DB white dwarfs (V777 Her or DBV variables) known so far. The detailed investigation of the short-period and low-amplitude pulsations...

White dwarf-main sequence (WDMS) binaries are used to study several different important open problems in modern astrophysics. The Sloan Digital Sky Survey (SDSS) identified the...

While the near-infrared wavelength regime is becoming more and more important for astrophysics there is a marked lack of spectrophotometric standard star data that allow to flux...

The Gaia space mission, through its 5-6 years survey of the whole sky up to magnitude V=20-25, will drastically increase the sample of known white dwarfs allowing to address new...

Hydrogen-rich, DA-type white dwarfs are particularly suited as primary standard stars for flux calibration. State-of-the-art NLTE models consider opacities of species up to...

We report photometric observations of the eclipsing close binary CSS21055 (SDSS J141126+200911) that strongly suggest that the companion to the carbon-oxygen white dwarf is a...

We report the effort to search for white dwarf p-mode oscillations in RX J2117.1+3412 (V2027 Cyg), a GW Vir star. The data were taken with Miosotys, a multi-fiber photometer,...

The number of detected extremely low mass (ELM) white dwarf stars has increased drastically in recent year thanks to the results of many surveys. In addition, some of these...

An accurate assessment of white dwarf cooling times is paramount so that white dwarf cosmochronology of Galactic populations can be put on more solid grounds. This issue is...

We present new diagnostics of white dwarf (WD) cooling sequences and luminosity functions (LFs) in the near-infrared (NIR) bands that will exploit the sensitivity and resolution...