Related papers: IP Eri: A surprising long-period binary system hos…

We describe radial velocity observations of a large sample of apparently single white dwarfs (WDs), obtained in a long-term effort to discover close, double-degenerate (DD) pairs which might comprise viable Type Ia Supernova (SN Ia)…

The white dwarf binary pathways survey is dedicated to studying the origin and evolution of binaries containing a white dwarf and an intermediate-mass secondary star of the spectral type A, F, G, or K (WD+AFGK). Here we present CPD-65\,264,…

EF Eri is a magnetic cataclysmic variable that has been in a low accretion state for the past nine years. Low state optical spectra reveal the underlying Zeeman-split white dwarf absorption lines. These features are used to determine a…

Binaries consisting of a hot subdwarf star and an accreting white dwarf (WD) are sources of gravitational wave radiation at low frequencies and possible progenitors of type Ia supernovae if the WD mass is large enough. Here, we report the…

We present results from our ongoing follow-up observations of double white dwarf binaries detected in the ESO SN Ia Progenitor SurveY (SPY). We discuss our observing strategy and data analysis and present the orbital solutions of five close…

We discovered Fe $K_{\alpha}$ complex emission and pulsation in two highly variable sources (4XMM J174917.7--283329, 4XMM J174954.6--294336). The equivalent widths of 6.4 and 6.7 keV lines of 4XMM J174917.7--283329 are $99^{+84}_{-72}$ and…

We report the detection of eclipses in LSPM J1112+7626, which we find to be a moderately bright (I_C = 12.14 +/- 0.05) very low-mass binary system with an orbital period of 41.03236 +/- 0.00002 days, and component masses M_1 = 0.395 +/-…

We report the discovery of the ultracompact hot subdwarf (sdOB) binary OW J074106.0-294811.0 with an orbital period of P$_{\rm orb}=44.66279\pm1.16\times10^{-4}$ min, making it the most compact hot subdwarf binary known. Spectroscopic…

We report the occurrence of a deep low state in the eclipsing short-period cataclysmic variable IR Com, lasting more than two years. Spectroscopy obtained in this state shows the system as a detached white dwarf plus low-mass companion,…

From the radial velocities of the N IV 4058 and He II 4686 emission lines, and the N V 4604-20 absorption lines, determined in digital spectra, we report the discovery that the X-ray bright emission line star Wack 2134 (= WR 21a) is a…

Spitzer Space Telescope IRAC 3-8 micron and AKARI IRC 2-4 micron photometry are reported for ten white dwarfs with photospheric heavy elements; nine relatively cool stars with photospheric calcium, and one hotter star with a peculiar high…

We announce the discovery of a new eclipsing hot subdwarf B + M dwarf binary, EC 10246-2707, and present multi-colour photometric and spectroscopic observations of this system. Similar to other HW Vir-type binaries, the light curve shows…

Five self-lensing binaries (SLBs) have been discovered with data from the \textit{Kepler} mission. One of these systems is KIC 8145411, which was reported to host an extremely low mass (ELM; $0.2\,M_{\odot}$) white dwarf (WD) in a 456-day…

Low-mass white dwarfs (LMWDs) are believed to be exclusive products of binary evolution, as the Universe is not yet old enough to produce them from single stars. Because of the strong tidal forces operating during the binary interaction…

The merger of close double white dwarfs (CDWDs) is one of the favourite evolutionary channels for producing Type Ia supernovae (SN Ia). Unfortunately, current theories of the evolution and formation of CDWDs are still poorly constrained and…

Hot subdwarf stars with F-K main sequence binary companions have been known for decades, but the first orbital periods for such systems were published just recently. Current observations suggest that most have long periods, on the order of…

The metal abundances in the atmospheres of hot white dwarfs (WDs) entering the cooling sequence are determined by the preceding Asymptotic Giant Branch (AGB) evolutionary phase and, subsequently, by the onset of gravitational settling and…

We describe a near-IR photometric search for cool red dwarf companions to hot EUV-detected white dwarfs (WDs). While some composite systems have been found optically among WDs detected in recent EUV All-Sky Surveys, we develop an IR…

White dwarfs with a F, G or K type companion represent the last common ancestor for a plethora of exotic systems throughout the galaxy, though to this point very few of them have been fully characterised in terms of orbital period and…

Among the 28,000 targeted stars in K2 Field 10 is the white dwarf WD 1202-024 (EPIC 201283111), first noted in the SDSS survey (SDSS 120515.80-024222.7). We have found that this hot white dwarf (Teff = 22,640 K) is in a very close orbit (P…