Related papers: Two New White Dwarfs With Variable Magnetic Balmer…
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…
Extensive observations from the Kepler spacecraft have recently revealed a new outburst phenomenon operating in cool pulsating DA (hydrogen atmosphere) white dwarfs (DAVs). With the introduction of two new outbursting DAVs from K2 Fields 7…
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…
There is solid observational evidence on the existence of massive, $M\sim 1~M_\odot$, highly magnetized white dwarfs (WDs) with surface magnetic fields up to $B\sim 10^9$ G. We show that, if in addition to these features, the star is fast…
We determine the orbits of four double degenerate systems (DDs), composed of two white dwarfs, and of two white dwarf -- M dwarf binaries. The four DDs, WD1022+050, WD1428+373, WD1824+040, and WD2032+188, show orbital periods of 1.157155(5)…
The magnetism and rotation of white dwarf (WD) stars are investigated in relation to a hydromagnetic dynamo operating in the progenitor during shell burning phases. The downward pumping of angular momentum in the convective envelope, in…
Spectrophotometric observations at high signal-to-noise ratio were obtained of a complete sample of 347 DA white dwarfs from the Palomar Green (PG) Survey. Fits of observed Balmer lines to synthetic spectra calculated from pure-hydrogen…
We report the first time-resolved photometric and spectroscopic optical observations of the X-ray source RX J2133.7+5107, identified in the ROSAT survey. A clear persistent optical light pulsation is discovered with fast photometry at a…
We performed an optical study of the magnetic period-bouncer candidate IL Leo. Long-term photometric analysis over $\approx 20$ years reveals multiple state transitions. Modelling the ultraviolet and optical spectral energy distribution…
This paper presents the results of a Spitzer IRAC 3-8 micron photometric search for warm dust orbiting 17 nearby, metal-rich white dwarfs, 15 of which apparently have hydrogen dominated atmospheres (type DAZ). G166-58, G29-38, and GD 362…
We report the discovery of a new metal-rich DAZ white dwarf, GD 362. High signal-to-noise optical spectroscopy reveals the presence of spectral lines from hydrogen as well as CaI, CaII, MgI, and FeI. A detailed model atmosphere analysis of…
Accurate tracers of the stellar magnetic field and rotation are cornerstones for the study of M dwarfs and for reliable detection and characterization of their exoplanetary companions. Such measurements are particularly challenging for old,…
We report the discovery of the ninth pre-polar, consisting of a late-type ZAMS secondary and a magnetic white dwarf. The white dwarf accretes at extreme low rate, dot{M} ~ 10**-14 Msun/yr, from the wind of the companion donor star. The…
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…
We report the detection of Zeeman-split Lalpha absorption pi and sigma+ lines in the far-ultraviolet Hubble Space Telescope/Space Telescope Imaging Spectrograph spectrum of the magnetic cataclysmic variable RX J1554.2+2721. Fitting the STIS…
I introduce the two classes of pulsar, white-dwarf binaries, and describe for each what we have learned from a specific system, PSR J1012+5307 and PSR B0655+64, respectively, summarising what has been done, presenting new results, and…
Since the large amplitude 2007 outburst which heated its accreting, pulsating white dwarf, the dwarf nova system GW Librae has been cooling to its quiescent temperature. Our Hubble Space Telescope ultraviolet spectra combined with…
We report the discovery of four massive ($M > 0.8\,M_\odot$) ZZ Ceti white dwarfs, including an ultramassive $1.16\,M_\odot$ star. We obtained ground based, time-series photometry for thirteen white dwarfs from the Sloan Digital Sky Survey…
WZ Sge-type dwarf novae form one of the most intriguing classes of compact accreting binaries. They are recognized as the most evolved population of hydrogen-rich cataclysmic variables. Yet they exhibit energetic disk-powered outbursts with…
We identify SDSSJ121010.1+334722.9 as an eclipsing post-common-envelope binary, with an orbital period of P ~ 3 hrs, containing a very cool, low-mass, DAZ white dwarf and a low-mass main-sequence star of spectral type M5. A model atmosphere…