Related papers: Modeling the Evolution of Silicate/Volatile Accret…
The photospheres of some white dwarfs are "polluted" by accretion of material from their surrounding planetary debris. White dwarfs with dust disks are often heavily polluted and high-resolution spectroscopic observations of these systems…
A non negligible fraction of white dwarf stars show the presence of heavy elements in their atmospheres. The most accepted explanation for this contamination is the accretion of material coming from tidally disrupted planetesimals, which…
The polluted white dwarf (WD) system SDSS J122859.93+104032.9 (SDSS J1228) shows variable emission features interpreted as originating from a solid core fragment held together against tidal forces by its own internal strength, orbiting…
Context. About 25% -- 50% of white dwarfs are found to be contaminated by heavy elements, which are believed to originate from external sources such as planetary materials. Elemental abundances suggest that most of the pollutants are rocky…
Recent observations, including those by JWST, suggest that the atmospheres of many gas giant exoplanets have super-stellar metallicity that is anti-correlated with planetary mass. Several studies suggest that the super-stellar metallicity…
Of the 21 known gaseous debris discs around white dwarfs, a large fraction of them display observational features that are well described by an eccentric distribution of gas. In the absence of embedded objects or additional forces, these…
We report the discovery of excess K-band radiation from a metal-rich DAV white dwarf star, WD1150-153. Our near infrared spectroscopic observations show that the excess radiation cannot be explained by a (sub)stellar companion, and is…
Spectroscopic observations of some metal-rich white dwarfs (WDs), believed to be polluted by planetary material, reveal the presence of compact gaseous metallic disks orbiting them. The observed variability of asymmetric, double-peaked…
Recent observations have uncovered a correlation between the accretion rates (measured from the UV continuum excess) of protoplanetary discs and their masses inferred from observations of the sub-mm continuum. While viscous evolution models…
Atmospheric heavy elements have been observed in more than a quarter of white dwarfs (WDs) at different cooling ages, indicating ongoing accretion of asteroidal material, whilst only a few per cent of the WDs possess a dust disk, and all…
Several white dwarfs with atmospheric metal pollution have been found to host small planetary bodies (planetesimals) orbiting near the tidal disruption radius. We study the physical properties and dynamical origin of these bodies under the…
The atmospheres of a large proportion of white dwarf stars are polluted by heavy elements that are expected to sink out of visible layers on short timescales. This has been interpreted as a signature of ongoing accretion of debris from…
Dozens of white dwarfs with anomalous metal polluted atmospheres (DZ WDs) are known to host dust and gas discs. The line profiles of the Ca II triplet emitted by the gas discs show significant asymmetry. Several minor planets have been…
Observationally inferred crystalline abundance in silicates in comets, which should have been formed in the outer region of a protoplanetary disk, is relatively high (~ 10-60%), although crystalline silicates would be formed by annealing of…
Collimated outflows from accreting white dwarfs have an important role to play in the study of astrophysical jets. Observationally, collimated outflows are associated with systems in which material is accreted though a disk. Theoretically,…
The metal-poor gas continuously accreting onto the discs of spiral galaxies is unlikely to arrive from the intergalactic medium (IGM) with exactly the same rotation velocity as the galaxy itself and even a small angular momentum mismatch…
Heavy elements are observed in the atmospheres of many DA and DB white dwarfs, and their presence is attributed to the accretion of matter coming from debris disks. Several authors have deduced accretion rates from the observed abundances,…
Polluted white dwarfs serve as astrophysical mass spectrometers - their photospheric abundances are used to infer the composition of planetary objects that accrete onto them. We show that due to asymmetries in the accretion process, the…
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…
It has long been accepted that a possible mechanism for explaining the existence of magnetic white dwarfs is the merger of a binary white dwarf system, as there are viable mechanisms for producing sustainable magnetic fields within the…