Related papers: Evidence for Gas from a Disintegrating Extrasolar …

Observations of debris disks, the products of the collisional evolution of rocky planetesimals, can be used to trace planetary activity across a wide range of stellar types. The most common end points of stellar evolution are no exception…

White dwarfs are routinely observed to have polluted atmospheres, and sometimes significant infrared excesses, that indicate ongoing accretion of circumstellar dust and rocky debris. Typically this debris is assumed to be in the form of a…

We have searched for evidence for dust and gas disks at a sample of hot DA white dwarfs 20 000K < Teff < 50 000K, without success. Although their atmospheres are polluted with heavy elements, we cannot yet convincingly and conclusively show…

Previously published observations of 60 externally-polluted white dwarfs show that none of the stars have accreted from intact refractory-dominated parent bodies composed mainly of Al, Ca and O, although planetesimals with such a…

About a dozen hot white dwarfs with effective temperatures Teff = 65,000-120,000 K exhibit unusual absorption features in their optical spectra. These objects were tentatively identified as Rydberg lines of ultra-high excited metals in…

In this article we describe the search for white dwarfs (WDs) in the multi-band photometric data of the Capodimonte deep field survey. The WD candidates were selected through the V-R_C vs B-V color-color diagram. For two bright objects, the…

WD J2356$-$209 is a cool metal-polluted white dwarf whose visible spectrum is dominated by a strong and broad sodium feature. Although discovered nearly two decades ago, no detailed and realistic analysis of this star had yet been realized.…

Between 25-50 % of white dwarfs (WD) present atmospheric pollution by metals, mainly by rocky material, which has been detected as gas/dust discs, or in the form of photometric transits in some WDs. Planets might be responsible for…

Spitzer Space Observatory IRAC and MIPS photometric observations are presented for 20 white dwarfs with T < 20,000 K and metal-contaminated photospheres. A warm circumstellar disk is detected at GD 16 and likely at PG 1457-086, while the…

We announce the discovery of the most massive pulsating hydrogen-atmosphere (DA) white dwarf (WD) ever discovered, GD 518. Model atmosphere fits to the optical spectrum of this star show it is a 12,030 +/- 210 K WD with a log(g) = 9.08 +/-…

We report the discovery of a third white dwarf hosting a gaseous debris disc, SDSSJ084539.17+225728.0. The typical double-peaked CaII 8498,8542,8662A emission lines can be modelled in terms of a Keplerian gas disc with a radial extent from…

Approximately 25-50% of white dwarfs (WDs) exhibit metal absorption lines in their photospheres, which are attributed to accretion from their remnant planetary systems. Although white dwarfs with detected planetary systems are more likely…

Polluted white dwarfs are generally accreting terrestrial-like material that may originate from a debris belt like the asteroid belt in the solar system. The fraction of white dwarfs that are polluted drops off significantly for white…

Using Keck/HIRES, we report abundances of 11 different elements heavier than helium in the spectrum of Ton 345, a white dwarf that has accreted one of its own minor planets. This particular extrasolar planetesimal which was at least 60% as…

White dwarfs with emission lines from gaseous debris discs are among the rarest examples of planetary remnant hosts, but at the same time they are key objects for studying the final evolutionary stage of planetary systems. Making use of the…

Asteroid material is detected in white dwarfs (WDs) as atmospheric pollution by metals, in the form of gas/dust discs, or in photometric transits. Within the current paradigm, minor bodies need to be scattered, most likely by planets, into…

A handful of white dwarfs with helium-dominated atmospheres contain exceptionally large masses of hydrogen in their convection zones, with the metal-polluted white dwarf GD 16 being one of the earliest recognised examples. We report the…

White dwarfs containing orbiting planetesimals or their debris represent crucial benchmarks by which theoretical investigations of post-main-sequence planetary systems may be calibrated. The photometric transit signatures of likely…

Astronomers have discovered thousands of planets outside the solar system, most of which orbit stars that will eventually evolve into red giants and then into white dwarfs. During the red giant phase, any close-orbiting planets will be…

Observations of heavy metal pollution in white dwarf stars indicate that metal-rich planetesimals are frequently scattered into star-grazing orbits, tidally disrupted, and accreted onto the white dwarf surface, offering direct insight into…