Iron abundance in the prototype PG1159 star, GW Vir pulsator PG1159-035, and related objects

TL;DR

This study measures iron abundances in PG1159 stars, including the prototype PG1159-035, revealing they have solar iron levels, challenging prior beliefs of iron deficiency in these stars.

Contribution

First detection of Fe VIII lines in PG1159 stars, establishing that these stars have solar iron abundance and are not iron deficient.

Findings

All four studied PG1159 stars have solar iron abundance.

Fe VIII and Fe VII lines detected in different stars.

Results challenge previous assumptions of iron deficiency.

Abstract

We performed an iron abundance determination of the hot, hydrogen deficient post-AGB star PG1159-035, which is the prototype of the PG1159 spectral class and the GW Vir pulsators, and of two related objects (PG1520+525, PG1144+005), based on the first detection of Fe VIII lines in stellar photospheres. In another PG1159 star, PG1424+535, we detect Fe VII lines. In all four stars, each within Teff = 110,000 - 150,000 K, we find a solar iron abundance. This result agrees with our recent abundance analysis of the hottest PG1159 stars (Teff = 150,000 - 200,000 K) that exhibit Fe X lines. On the whole, we find that the PG1159 stars are not significantly iron deficient, in contrast to previous notions.