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

CORSICO, A. H.; ALTHAUS, L. G.; MILLER BERTOLAMI, M. M.; GARCIA-BERRO, E.

Barcelona, Espana

Workshop; 16th European White Dwarf Workshop; 2008

IEEC

We re-examine the theoretical instability strip of pulsating DB (He-dominated atmospheres) white dwarfs, commonly known as  DBV (or V777 Her) variable stars. We performed an extensive g-mode non-adiabatic pulsation analysis on a new generation of full DB white dwarf evolutionary models spanning a wide range of stellar masses (0.530 to 0.870 Mo), 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, and finally the DB white dwarf domain have been considered. We explicitly accounted for the evolution of the chemical abundance distribution due to time-dependent chemical diffusion processes. In this poster we present our first results about  the effects of different prescriptions of the MLT theory of convection on the precise location of the blue edge of the DBV instability strip. We are planning to explore in brief the impact of  the Canuto-Goldman-Mazzitelli (CGM) theory of convection on the theoretical DBV instability strip.