Gaseous disks in white dwarfs

L. SAKER, L. GARCÍA, M. GOMEZ

La Laguna

Otro; XXIX Canary Islands Winter School of Astrophysics: Applications of Radiative Transfer to stellar and planetary atmospheres; 2017

Instituto de Astrofísica de Canarias

In recent years, thanks to Spitzer and WISE, the number of white dwarfs(WDs) with IR excesses attributed to the presence of a debris disk, has increased significantly. Additionally, disks of gas were found in a handful of WDs with debris disks, through detection of emission lines of Ca triplet in 860 nm (distinctive of a gas in a Keplerianstable rotating disk). However, not all WDs with debris disks has a gas disk, which suggests that the production mechanism of the gaseous disks is not universal. At the present time, it still remains unknown why WDs of similar characteristics retain their gas disks and other do not, although several scenarios have been proposed. One manner to infer some constraints or hits to help clarify this issue is to analyze and confront significant groups of both types of objects. In this context, we have obtained GMOS/GEMINI optical spectra for a sample of 9 WDs with IR excess, selected from our sample of 29 debris disks WDs, to find the gas counterpart to the dusty disks. We combined our sample with other objects from the literature and analyze the largest available sample to find key characteristics to better understand gas disks in WDs.