Related papers: Monitoring and modelling of white dwarfs with extr…
(ABRIDGED) We report here our mapping of the magnetic field topology of the M4 dwarf G 164-31 (or Gl 490B), which is expected to be fully convective, based on time series data collected from 20 hours of observations spread over 3 successive…
Binaries of two white dwarfs (WDs) are an important class of astrophysical objects that are theorized to lead to Type Ia supernovae and are also used to gain insight into complex processes involved in stellar binary evolution. We report the…
We present results from a circular polarimetric survey of candidate detached magnetic white dwarf - M dwarf binaries obtained using the Nordic Optical Telescope, La Palma. We obtained phase resolved spectropolarimetry and imaging…
Weak magnetic fields have recently been detected in Vega and Sirius. Here, we explore the possibility that these fields are the remnants of some field inherited or created during or shortly after star formation and, unlike true fossil…
Recent studies of the stellar population in the solar neighborhood (<20 pc) suggest that there are undetected white dwarfs (WDs) in multiple systems with main sequence companions. Detecting these hidden stars and obtaining a more complete…
Radio observations at low frequencies are sensitive to the magnetic activity of stars and the plasma environment surrounding them. The accurate interpretation of the processes underlying the radio signatures requires a detailed…
We present the first radiation magnetohydrodynamics simulations of the atmosphere of white dwarf stars. We demonstrate that convective energy transfer is seriously impeded by magnetic fields when the plasma-beta parameter, the thermal to…
In a volume-limited sample of 63 ultracool dwarfs of spectral type M7-M9.5, we have obtained high-resolution spectroscopy with UVES at the Very Large Telescope and HIRES at Keck Observatory. In this second paper, we present projected…
We have computed optical Zeeman spectra of magnetic white dwarfs for field strengths between 10 and 200MG and effective temperatures between 8000 and 40000K. They form a database containing 20628 sets of flux and circular polarization…
The recent discovery of a weak surface magnetic field on the normal intermediate-mass star Vega raises the question of the origin of this magnetism in a class of stars that was not known to host magnetic fields. We aim to confirm the field…
Stellar dynamos generate magnetic fields that are of fundamental importance to the variability and evolution of Sun-like and low-mass stars, and for the development of their planetary systems. We report measurements of surface-average…
We used the optical and near-infrared imagers located on the Liverpool, the IAC80, and the William Herschel telescopes to monitor 18 M7$-$L9.5 dwarfs with the objective of measuring their rotation periods. We achieved accuracies typically…
We report on the spectroscopic confirmation of 68 new bright ($G=13.5-17.2$ mag) and blue (pre-)white dwarfs (WDs). This finding has allowed us to almost double the number of the hottest ($T_{\mathrm{eff}} \geq 60$kK) known WDs brighter…
We aim at a highly sensitive search for weak magnetic fields in main sequence stars of intermediate mass, by scanning classes of stars with no previously reported magnetic members. After detecting a weak magnetic field on the normal,…
Magnetic cataclysmic variables are close binaries which consist of a compact object - a white dwarf - and a red dwarf filling its Roche Lobe. Such systems are physical laboratories which enable study of the influence of magnetic fields on…
Characterizing the local space density of double degenerate binary systems is a complementary approach to broad sky surveys of double degenerates to determine the expected rates of white dwarf binary mergers, in particular those that may…
We have used 605 days of photometric data from the Kepler spacecraft to study KIC 6614501, a close binary system with an orbital period of 0.15749747(25) days (3.779939 hours), that consists of a low-mass subdwarf B (sdB) star and a white…
We study the evolution of white dwarf (WD) magnetic fields that originate from core-convective dynamos during the main-sequence. Using stellar evolution and WD cooling models combined with magnetic field diffusion calculations, we…
White dwarf WD 1145+017 is orbited by several clouds of dust, possibly emanating from actively disintegrating bodies. These dust clouds reveal themselves through deep, broad, and evolving transits in the star's light curve. Here, we report…
SDSSJ125733.63+542850.5 (hereafter SDSSJ1257+5428) is a compact white dwarf binary from the Sloan Digital Sky Survey that exhibits high-amplitude radial velocity variations on a period of 4.56 hours. While an initial analysis suggested the…