Seismological constraints on the high-gravity GW Vir stars PG 2131+066 and PG 1707+427

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

Barcelona, Espana

Workshop; 16th European White Dwarf Workshop; 2008

IEEC

we present an ateroseismological study on the two high-gravity pulsating PG1159 (or DOV) stars PG 2131+066 and PG 1707+427. Our study is based on the full  PG1159 evolutionary models of Miller  Bertolami & Althaus  (2006). We computed adiabatic g-mode pulsation periods on PG1159 evolutionary models with stellar masses spanning the range 0.530 to 0.741  Mo. We derive the stellar mass from the period spacing data (METHODS 1 and 2 below). We also  employ the individual observed periods to find representative asteroseismological models for each star (METHOD 3 below). These models reproduce the observed  period patterns of each star with an average of the period differences of 1.57 s (for PG 2131+066) and 1.75 s (for PG 1707+427). The seismological model for PG 2131+066 has an effective temperature of 102000 K, a stellar mass  0.589 Mo, a surface gravity log g= 7.63, and  a He-rich  envelope thickness of Menv=  0.016 Mo. The seismological model for PG 1707+427 has an effective temperature of 89500 K, a stellar mass 0.542 Mo, a surface gravity log g= 7.53, and  a He-rich  envelope thickness of Menv=  0.025 Mo.  From the luminosity of our seismological models we derive independent distances and parallaxes.