IALP   13078
INSTITUTO DE ASTROFISICA LA PLATA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Asteroseismological modeling of PG1159+035, the prototype of of the GW Vir stars
Autor/es:
A. H. CÓRSICO; L. G. ALTHAUS; M. M. MILLER BERTOLAMI; S. O. KEPLER; J. E. S. COSTA
Lugar:
Tübingen, Germany
Reunión:
Conferencia; Hydrogen Deficient stars; 2007
Institución organizadora:
Institut für Astronomie und Astrophysik Tübingen
Resumen:
We present an asteroseismological study on PG 1159-035 the prototype of the GW Vir variable stars on the basis of detailed and full PG1159 evolutionary models recently presented by Miller Bertolami & Althaus (2006). We carried out extensive g-mode adiabatic period computations on PG1159 evolutionary modelswith stellar masses spanning the range 0.530 to 0.741M. These models are derived from the complete evolution of progenitor stars, including the thermally pulsing AGB phase and born-again episode. We first constrain the stellar mass of PG 1159−035 by comparing the observed period spacing with the asymptotic period spacing and with the average of the computed period spacings. In this way we derive a stellar mass in the range 0.56 − 0.59M. We also employ the individual observed periods reported recently by Costa et al. (2007) and found a representative seismological model for PG 1159−035 which nicely reproduces the observed period pattern. The model has an effective temperature Teff = 127 680 K, a stellar mass M = 0.565M, a surface gravity log g = 7.42, a stellar luminosity and radius log(L/L) = 2.15 and log(R/R) = −1.62, respectively, and a He-rich envelope thickness Menv = 0.017M. Nonadiabatic calculations predict that this asteroseismological model is pulsationally stable against dipole (` = 1) modes,contradicting the observational evidence. In addition, all of the theoretical pulsation modes are characterized by positive rates of period changes, at odds with the recent measurements by Costa & Kepler (2007).