Related papers: Finding compact hot subdwarf binaries in the Galac…

Hot subdwarfs are considered to be the compact helium cores of red giants, which lost almost their entire hydrogen envelope. What causes this enormous mass loss is still unclear. Binary interactions are invoked and a significant fraction of…

We report on 2MASS J01542930+0053266, a faint eclipsing system composed of two M dwarfs. The variability of this system was originally discovered during a pilot study of the 2MASS Calibration Point Source Working Database. Additional…

The rapid rotation of Be stars may be caused in some cases by past mass and angular momentum accretion in an interacting binary in which the mass donor is currently viewed as a small, hot subdwarf stripped of its outer envelope. Here we…

Hot subdwarfs (sdO/Bs) are the helium-burning cores of red giants, which lost almost all of their hydrogen envelopes. This mass loss is often triggered by common envelope interactions with close stellar or even substellar companions. Cool…

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…

Using data from the extended Kepler mission in K2 Campaign 10 we identify two eclipsing binaries containing white dwarfs with cool companions that have extremely short orbital periods of only 71.2 min (SDSS J1205-0242, a.k.a. EPIC…

The masses of compact objects like white dwarfs, neutron stars and black holes are fundamental to astrophysics, but very difficult to measure. We present the results of an analysis of subluminous B (sdB) stars in close binary systems with…

We present a spectroscopic investigation of the Be+sdO binary system HR 2142 that is based upon large sets of ultraviolet observations from the International Ultraviolet Explorer and ground-based H-alpha observations. We measured radial…

About 50% of all known hot subdwarf B stars (sdBs) reside in close (short period) binaries, for which common envelope ejection is the most likely formation mechanism. However, Han et al. 2003 predict that the majority of sdBs should form…

Planets and brown dwarfs in close orbits will interact with their host stars, as soon as the stars evolve to become red giants. However, the outcome of those interactions is still unclear. Recently, several brown dwarfs have been discovered…

ZTF J213056.71+442046.5 is the prototype of a small class of recently discovered compact binaries composed of a white dwarf and a hot subdwarf that fills its Roche-lobe. Its orbital period of only 39 min is the shortest known for the…

We present time-series spectroscopy and photometry of Gaia DR2 6097540197980557440, a new deeply-eclipsing hot subdwarf B (sdB) + M dwarf (dM) binary. We discovered this object during the course of the Eclipsing Reflection Effect Binaries…

We measured projected rotational velocities of more than a hundred apparently single sdBs. A comparison is made with sdB stars in binary systems with orbits so wide, that tidal interaction becomes negligible. All of these stars are slow…

Hot subdwarf binaries with white dwarf companions with orbital periods of less than two hours are progenitor candidates for massive single white dwarfs as well as a variety of thermonuclear explosions. Our aim is to determine the binary…

Hot subdwarf (sdB) stars in binary systems with main-sequence (MS) companions provide valuable insights into mass transfer and envelope ejection processes in binary evolution. Their mass ratios, orbital periods, and stellar properties…

We report on the results we obtained with XMM-Newton observations of HD49798 and BD+37 442, the only two sdO stars for which X-ray emission has been observed so far. HD is a single-lined spectroscopic binary with orbital period of 1.5 days.…

We report the discovery of a new detached, double white dwarf system with an orbital period of 39.8 min. We targeted SDSS J163030.58+423305.8 (hereafter J1630) as part of our radial velocity program to search for companions around low-mass…

We present high-speed ULTRACAM and SOFI photometry and X-shooter spectroscopy of the recently discovered 94 minute orbital period eclipsing white dwarf / main-sequence binary SDSS J085746.18+034255.3 (CSS 03170) and use these observations…

Hot subdwarf stars (sdO/Bs) are the stripped cores of red giants located at the bluest extension of the horizontal branch. They constitute the dominant population of UV-bright stars in old stellar environments and are most likely formed by…

The origin of hot subdwarf B stars (sdBs) is still unclear. About half of the known sdBs are in close binary systems for which common envelope ejection is the most likely formation channel. Little is known about this dynamic phase of binary…