Asymmetric Line Profiles in Spectra of Gaseous Metal Disks Around Single White Dwarfs

TL;DR

This paper models asymmetric spectral line profiles in gaseous metal disks around white dwarfs, suggesting non-axisymmetric disk geometries can explain observed spectral asymmetries.

Contribution

It introduces a modified accretion disk model to simulate non-axisymmetric geometries, successfully reproducing observed spectral asymmetries in white dwarf disks.

Findings

Model reproduces observed line asymmetries

Non-axisymmetric disk geometries are plausible explanations

Good agreement between simulations and observations

Abstract

Around several single DAZ and DBZ white dwarfs metal-rich disks have been observed, which are mostly believed to originate from disruption of smaller rocky planetesimals. In some cases the material does not (only) form a dusty but gaseous disk. In the case of SDSS J122859.93+104032.9 the double peaked infrared Ca II triplet at about 8500 angstrom, one of only two emission features of the spectra, exhibits a strong red/violet asymmetry. Assuming a composition similar to a chondrite-like asteroid, being the most prominent type in our own solar system, we calculated the spectrum and vertical structure of the disk using the Tuebingen NLTE accretion disk code "AcDc". Modified to simulate different non axis-symmetrical disk geometries, the first preliminary results are in good agreement with the observed asymmetric line profile.