Hydrogen deficient low mass white dwarfs, the descendants of PG1159 stars or He-sdO/B stars?

BATTICH, TIARA; ALEJANDRO H. CÓRSICO; ALTHAUS, LEANDRO G.

del Norte, Armagh

Congreso; 4th Meeting on Hydrogen Deficient Stars; 2018

Hydrogen(H)-deficient white dwarfs (WDs) exhibit a variety of spectral classes. Among them, there are the DO WDs (45000 K < T eff < 200000 K), DB WDs (11000 K < T eff < 45000 K), and other WDs with mainly carbon or oxygen in their spectra. In this work we are interested in those rich in helium (He) (DO and DB WDs), in particular, those with masses below 0.5 M sun. These WDs were proposed to be the descendants of low mass PG1159 stars, or He-sdO stars. There exist in the literature detailed WD models evolved from PG1159 stars; however, detailed models of WDs coming from He-sdO stars are lacking. Also, it is worth exploring asteroseismology as a tool for distinguishing between these two scenarios in the WDs stage. Different physical processes that take place in the interior of the progenitor stars would lead to different configurations of the chemical profiles of low-mass WDs. These differences could have a distinct impact on the pulsational properties of the WDs. We compute for the first time WD models that come from He-sdO stars and envisage possible asteroseismological tools that could help to distinguish between post-PG1159 low-mass WD stars from post-He-sdO low-mass WD stars. We present here our preliminary studies.