Asteroseismological measurements on PG 1159-035, the prototype of the GW Vir variable stars

TL;DR

This study performs detailed asteroseismological analysis on PG 1159-035, deriving stellar parameters and comparing model predictions with observations, revealing insights into its internal structure and pulsation characteristics.

Contribution

It provides a comprehensive asteroseismological model for PG 1159-035 using full evolutionary models and extensive pulsation computations, improving understanding of its stellar parameters.

Findings

Derived stellar mass range 0.56-0.59 Mo from period-spacing data.

Best-fit model reproduces observed periods with average differences of 0.64-1.03 s.

Predicted positive period change rates, conflicting with some observations.

Abstract

An asteroseismological study of PG 1159-035, the prototype of the GW Vir variable stars, has been performed on the basis of detailed and full PG1159 evolutionary models presented by Miller Bertolami & Althaus (2006). We carried out extensive computations of adiabatic g-mode pulsation periods on PG1159 evolutionary models with stellar masses spanning the range 0.530 to 0.741 Mo. We derive a stellar mass in the range 0.56-0.59 Mo from the period-spacing data alone. We also find, on the basis of a period-fit procedure, a seismic model representative of PG 1159-035 that reproduces the observed period pattern with an average of the period differences of 0.64-1.03 s, consistent with the expected model uncertainties. The results of the period-fit analysis carried out in this work suggest that the surface gravity of PG 1159-035 would be 1 sigma larger than the spectroscopically inferred gravity. For our best-fit model of PG 1159-035, all of the pulsation modes are characterized by positive rates of period changes, at odds with the measurements by Costa & Kepler (2007).