Asteroseismic inferences on GW Vir variable stars in the frame of new PG 1159 evolutionary models

A. H. CÓRSICO; L. G. ALTHAUS

ASTRONOMY AND ASTROPHYSICS

EDP Sciences

Lugar: Les Ulis, France; Año: 2006 vol. 454 p. 863 - 881

0004-6361

An adiabatic, nonradial pulsation study  of GW Vir stars is presented.   The pulsation calculations are based on PG1159 evolutionary sequences with different stellar masses artificially derived from a full evolutionary sequence of 0.5895 Mo that has been computed taking into account the evolutionary history of the progenitor star. The artificial  sequences were constructed by appropriately  scaling the stellar mass of the 0.5895 Mo sequence well  before the modelsreach the low-luminosity, high-gravity stage of the GW Vir domain. We compute  g-mode pulsation  periods  appropriate to  GW Vir  variable stars.  The  implications for the  mode-trapping properties of  our PG 1159 models are  discussed at length. We found  that the mode-trapping features characterizing  our PG  1159 models are  mostly fixed  by the stepped shape  of the core  chemical profile left by  prior convective overshooting.  This  is particularly  true at least  for the  range ofperiods observed in  GW Vir stars. In addition,  we make asteroseismic inferences  about  the internal  structure  of  the  GW Vir  stars  PG 1159-035, PG 2131+066, PG 1707+427 and PG 0122+200.