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

TL;DR

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

Contribution

It introduces modifications to the AcDc code to simulate non-axis-symmetrical disk geometries, providing the first preliminary match to observed asymmetric line profiles.

Findings

Good agreement between simulated and observed asymmetries

Modified code successfully models non-axis-symmetrical disk structures

Supports the hypothesis of non-uniform disk geometries causing spectral asymmetries

Abstract

Metal-rich debris disks were discovered around several single DAZ and DBZ white dwarfs, which may stem from disruption of smaller rocky planetesimals. In some cases, the material in addition forms a gaseous disk. For SDSS J122859.93+104032.9, the double peaked infrared Ca II triplet at about 8500 angstrom exhibits a strong red/violet asymmetry. With the Tuebingen non-LTE Accretion Disk code AcDc we calculated the spectrum and vertical structure of the disk, assuming the chemical mixture of the disk's material being similar to a chondrite-like asteroid, the most prominent type in our own solar system. By modifying the code to simulate different non axis-symmetrical disk geometries, the first preliminary results are in good agreement with the observed asymmetric line profile.