Related papers: The critical binary star separation for a planetar…
The statistical properties of planets in binaries were investigated. Any difference to planets orbiting single stars can shed light on the formation and evolution of planetary systems. As planets were found around components of binaries…
The destiny of planetary systems through the late evolution of their host stars is very uncertain. We report a metal-rich gas disk around a moderately hot and young white dwarf. A dynamical model of the double-peaked emission lines…
White dwarfs are compact objects with atmospheres containing mainly light elements, hydrogen or helium. Because of their surface high gravitational field, heavy elements diffuse downwards in a very short timescale compared to the…
We compute that extrasolar minor planets can retain much of their internal H_2O during their host star's red giant evolution. The eventual accretion of a water-rich body or bodies onto a helium white dwarf might supply an observable amount…
We present HST ultraviolet spectroscopy of the white dwarfs PG0843+516, PG1015+161, SDSS1228+1040, and GALEX1931+0117, which accrete circumstellar planetary debris formed from the destruction of asteroids. Combined with optical data, a…
It is difficult to study the interiors of terrestrial planets in the Solar System and the problem is magnified for distant exoplanets. However, sometimes nature is helpful. Some planetary bodies are torn to fragments and consumed by the…
A large fraction of white dwarfs are accreting or have recently accreted rocky material from their planetary systems, thereby polluting their atmospheres with elements heavier than helium. In recent years, the quest for mechanisms that can…
Extensive photometric stellar surveys show that many main sequence stars show emission at infrared and longer wavelengths that is in excess of the stellar photosphere; this emission is thought to arise from circumstellar dust. The presence…
Although 25%-50% of white dwarfs (WDs) display evidence for remnant planetary systems, their orbital architectures and overall sizes remain unknown. Vibrant close-in (~1 Solar radius) circumstellar activity is detected at WDs spanning many…
Over 1500 DBZ or DZ white dwarfs (WDs) have been observed so far, and polluted atmospheres with metal elements have been found among these WDs. The surface heavy element abundances of known DBZ or DZ WDs show an evolutionary sequence. By…
We examine recent studies on the formation rate of planetary nebulae and find this rate to be about one-third of the formation rate of white dwarfs. This implies than only about one-third of all planetary nebulae that evolve to form white…
The fraction of white dwarfs found in wide binaries is estimated by cross referencing a catalogue of wide binaries with catalogues photometrically determined white-dwarf candidates and spectroscopically confirmed white dwarf stars. The…
The population of compact binaries in dense stellar systems is affected strongly by frequent dynamical interactions between stars and their interplay with the stellar evolution. In this contribution, we consider these effects on binaries…
Spurred by the discovery of numerous exoplanets in multiple systems, binaries have become in recent years one of the main topics in planet formation research. Numerous studies have investigated to what extent the presence of a stellar…
There is increasing evidence for the presence and variability of circumstellar dust and gas around white dwarfs that are polluted with exoplanetary material, although the origin of this dust and gas remains debated. This paper presents the…
Brown dwarfs and giant planets orbiting close to a host star are subjected to significant irradiation that can modify the properties of their atmospheres. In order to test the atmospheric models that are used to describe these systems, it…
Almost every known planet host will evolve into a white dwarf, and the surviving planetary material will continue to orbit this stellar remnant. Asteroids perturbed onto star-grazing orbits will become disrupted, forming an accretion disk…
The formation of massive stars in close binary systems is complicated due to their high radiation pressure, the crowded environment and the expected minimum separation for fragmentation being many times greater than the orbital separation.…
Accretion-driven spin-up of a magnetized white dwarf in a close binary system is discussed. We address a situation in which the magnetic field of the white dwarf is screening during the accretion phase and re-generating due to the field…
We have gathered a sample of 112 main-sequence stars with known debris disks. We collected published information and performed adaptive optics observations at Lick Observatory to determine if these debris disks are associated with binary or…