Hot white dwarfs and pre-white dwarfs discovered with SALT
Werner, K.; Jeffery, C. S.; Miszalski, B.; Kilkenny, D.; Snowdon, E. J.; Monageng, I.
United Kingdom, Germany, South Africa, Australia
Abstract
The Southern African Large Telescope survey of helium-rich hot subdwarfs aims to explore evolutionary pathways among groups of highly evolved stars. The selection criteria mean that several hot white dwarfs and related objects have also been included. This paper reports the discovery and analysis of eight new very hot white dwarf and pre-white dwarf stars with effective temperatures exceeding 100 000 K. They include two PG1159 stars, one DO white dwarf, three O(He), and two O(H) stars. One of the O(H) stars is the central star of a newly discovered planetary nebula, and the other is the hottest 'naked' O(H) star. Both of the PG1159 stars are GW Vir variables, one being the hottest GW Vir star measured and a crucial test for pulsation stability models. The DO white dwarf is also the hottest in its class.