Related papers: Discovery of a stripped red giant core in a bright…
We have identified a star in the WASP archive photometry with an unusual lightcurve due to the total eclipse of a small, hot star by an apparently normal A-type star and with an orbital period of only 0.668d. From an analysis of the WASP…
The star 1SWASP J024743.37-251549.2 was recently discovered to be a binary star in which an A-type dwarf star eclipses the remnant of a disrupted red giant star (WASP0247-25B). The remnant is in a rarely-observed state evolving to higher…
We present an analysis of the evolutionary and pulsation properties of the extremely low-mass white dwarf precursor (B) component of the double-lined eclipsing system WASP 0247-25. Given that the fundamental parameters of that star have…
Subdwarf B stars are core-helium burning stars located on the extreme horizontal branch. Extensive mass loss on the red giant branch is necessary to form them. It has been proposed that substellar companions could lead to the required…
The star 1SWASP J162842.31+101416.7 (WASP 1628+10) is one of several EL CVn-type stars recently identified using the WASP database, i.e., an eclipsing binary star in which an A-type dwarf star (WASP 1628+10A) eclipses the remnant of a…
In the past, SDSS J160429.12+100002.2 was spectroscopically classified as a blue horizontal branch (BHB) star. Assuming a luminosity that is characteristic of BHB stars, the object's radial velocity and proper motions from Gaia Early Data…
We report the first $BV$ light curves and high-resolution spectra of the post-mass transfer binary star WASP 0131+28 to study the absolute properties of extremely low-mass white dwarfs. From the observed spectra, the double-lined radial…
We report the discovery of a stripped giant + lower giant binary, 2M04123153+6738486 (2M0412), identified during a search for non-interacting compact object-star binaries. 2M0412 is an evolved ($T_{\rm eff, giant}\simeq4000$ K), luminous…
Hot subdwarf B stars (sdBs) are core helium-burning stars located on the extreme horizontal branch. About half of the known sdB stars are found in close binaries. Their short orbital periods of 1.2 h to a few days suggest that they are post…
We report the discovery of 2M0056-08 as an equal-mass eclipsing binary (EB), comprising two red straggler stars (RSSs) with an orbital period of 33.9 d. Both stars have masses of 1.419 Msun, identical to within 0.2%. Both stars appear to be…
Some gaps in the mosaic of binary star evolution have recently been filled by the discoveries of helium-core white dwarf progenitors (often called extremely low mass (ELM) white dwarfs) as stripped cores of first-giant branch objects. Two…
The formation of hot subdwarf stars (sdBs), which are core helium-burning stars located on the extended horizontal branch, is still not understood. Many of the known hot subdwarf stars reside in close binary systems with short orbital…
Hot subdwarf B stars (sdBs) are evolved, core helium-burning objects located on the extreme horizontal branch. Their formation history is still puzzling as the sdB progenitors must lose nearly all of their hydrogen envelope during the…
We analyze the spectrum of an unusually-low mass white dwarf, SDSSJ123410.37-022802.9 (0335-264-52000), found in our recent, white dwarf catalog from the SDSS DR1 data release. Two independent, model atmosphere fits result in an accurate…
We report the discovery of a transiting planet with an orbital period of 1.36d orbiting the brighter component of the visual binary star BD -07 436. The host star, WASP-77A, is a moderately bright G8V star (V=10.3) with a metallicity close…
Approximately 150 low-mass white dwarfs, with masses below 0.4Msun, have been discovered. The majority of these low-mass WDs are observed in binary systems as they cannot be formed through single-star evolution within the Hubble time. In…
We started a new project which aims to find compact hot subdwarf binaries at low Galactic latitudes. Targets are selected from several photometric surveys and a spectroscopic follow-up campaign to find radial velocity variations on…
Hot subdwarf B stars (sdBs) are extreme horizontal branch stars believed to originate from close binary evolution. Indeed about half of the known sdB stars are found in close binaries with periods ranging from a few hours to a few days. The…
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…
Low mass white dwarfs are the remnants of disrupted red giant stars in binary millisecond pulsars and other exotic binary star systems. Some low mass white dwarfs cool rapidly, while others stay bright for millions of years due to stable…