Chandra and FUSE spectroscopy of the hot bare stellar core H 1504+65 *
1
Institut für Astronomie und Astrophysik, Universität Tübingen, Sand 1, 72076 Tübingen, Germany
2
Dr.-Remeis-Sternwarte, Universität Erlangen-Nürnberg, Sternwartstraße 7, 96049 Bamberg, Germany
3
Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH, UK
4
Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA
Corresponding author: K. Werner, werner@astro.uni-tuebingen.de
Received:
27
January
2004
Accepted:
6
April
2004
H 1504+65 is an extremely hot hydrogen-deficient white dwarf with an effective temperature close to 200 000 K. We present new FUV and soft X-ray spectra obtained with FUSE and Chandra, which confirm that H 1504+65 has an atmosphere primarily composed of carbon and oxygen. The Chandra LETG spectrum (60–160 Å) shows a wealth of photospheric absorption lines from highly ionized oxygen, neon, and – for the first time identified in this star – magnesium and suggests relatively high Ne and Mg abundances. This corroborates an earlier suggestion that H 1504+65 represents a naked C/O stellar core or even the C/O envelope of an O-Ne-Mg white dwarf.
Key words: stars: abundances / stars: atmospheres / stars: evolution / stars: AGB and post-AGB / stars: white dwarfs / stars: individual: H 1504+65
© ESO, 2004