Related papers: Detection of additional Be+sdO systems from IUE sp…
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…
Hot subdwarfs (sdBs) are core helium-burning stars, which lost almost their entire hydrogen envelope in the red-giant phase. Since a high fraction of those stars are in close binary systems, common envelope ejection is an important…
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…
About a third of the hot subdwarfs of spectral type B, which are mostly core-helium burning objects on the extreme horizontal branch, are found in close binaries with cool, low-mass stellar, substellar, or white dwarf companions. They can…
Hot subdwarf B (sdB) stars are evolved, subluminous, helium-burning stars, most likely formed when red-giant stars lose their hydrogen envelope via interactions with close companions. They play an important role in our understanding of…
We report on a search for evidence of binarity in Far-Ultraviolet Spectroscopic Explorer (FUSE) observations of DAO white dwarfs. Spectra recorded by FUSE are built up from a number of separate exposures. Observation of changes in the…
Hot subdwarf stars (sdO/Bs) are evolved core helium-burning stars with very thin hydrogen envelopes, which can be formed by common envelope ejection. Close sdB binaries with massive white dwarf (WD) companions are potential progenitors of…
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…
We present the results of a radial velocity (RV) survey of 46 subdwarf B (sdB) and 23 helium-rich subdwarf O (He-sdO) stars. We detected 18 (39%) new sdB binary systems, but only one (4%) He-sdO binary. Orbital parameters of nine sdB and…
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…
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…
Rapid rotation and nonradial pulsations enable Be stars to build decretion disks, where the characteristic line emission forms. A major but unconstrained fraction of Be stars owe their rapid rotation to mass and angular-momentum transfer in…
The number of spatially unresolved white dwarf plus main-sequence star binaries has increased rapidly in the last decade, jumping from only ~30 in 2003 to over 3000. However, in the majority of known systems the companion to the white dwarf…
Many classical Be stars acquire their very rapid rotation by mass and angular-momentum transfer in massive binaries. Short-lived intermediate-phase objects have only been discovered recently. Data archives and the literature have been…
Hot subluminous stars (sdO/B) are evolved low mass stars originating from red giants that lost their envelope almost entirely. The multitude of observed phenomena imply that several pathways may form hot subdwarfs, most involving close…
The project Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS (MUCHFUSS) aims at finding hot subdwarf stars with massive compact companions (white dwarfs with masses $M>1.0 {\rm M_{\odot}}$, neutron stars or black holes).…
182 single-lined hot subdwarf stars are identified by using spectra from the sixth and seventh data release (DR6 and DR7) of the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) survey. We classified all the hot subdwarf…
We report the discovery of the first hot subdwarf B (sdB) star with a massive compact companion in a wide ($P=892.5\pm60.2\,{\rm d}$) binary system. It was discovered based on an astrometric binary solution provided by the Gaia mission Data…
We have completed a survey of twenty-two ultraviolet-selected hot subdwarfs using the Fiber-fed Extended Range Optical Spectrograph (FEROS) and the 2.2-m telescope at La Silla. The sample includes apparently single objects as well as hot…
Multiple radial velocity observations have been obtained for a large sample of local field subdwarf B (sdB) stars over a period of two years. SdB stars appear to fall into three distinct groups based on their kinematic and spectroscopic…