Revisiting the theoretical DBV (V777 Her) instability strip: the MLT theory of convection

Understand

We reexamine the theoretical instability domain of pulsating DB white dwarfs (DBV or V777 Her variables).

• We performed an extensive $g$-mode nonadiabatic pulsation analysis of DB evolutionary models considering a wide range of stellar masses, for which the complete evolutionary stages of their progenitors from the ZAMS, through the thermally pulsing AGB and born-again phases, the domain of the PG1159 stars, the hot phase of DO white dwarfs, and then the DB white dwarf stage have been considered.
• We explicitly account for the evolution of the chemical abundance distribution due to time-dependent chemical diffusion processes.
• We examine the impact of the different prescriptions of the MLT theory of convection and the effects of small amounts of H in the almost He-pure atmospheres of DB stars on the precise location of the theoretical blue edge of the DBV instability strip.