Institute of Astronomy

Spectral modeling of gaseous, planetary debris disks around white dwarfs

SpeakerTalk DateTalk Series
Stephan Hartmann30 July 2014Across HR 2014 Talks


Planetary systems may survive their host star's final evolution stages. The numerous dusty debris disks orbiting single white dwarfs can be seen as evidence for remnant planets after the formation of the compact object. A handful of these systems host an additional gaseous debris disk, offering us the unique possibility to directly analyze the metal-rich debris content. Here we present our latest models of such metal-rich, gas disks around single white dwarfs. Using the Tübingen accretion disk code AcDc, we calculated synthetic spectra for different chemical compositions, surface densities, effective temperatures, and various radial extent. Tailoring the models to fit the hallmarking Ca II infrared triplet (at 8498, 8542, 8662 angstrom) of the observational data, we found the disks to be rather warm (about 6000 K) and low on density (below 0.3 g/cm^2). The total gas mass and the chemical composition are similar to those of average solar planetesimals, supporting the picture of remnant planetary material orbiting the white dwarf.