Understanding the spectrum of the very hot DA white dwarf PG0948+534 [SSA]

http://arxiv.org/abs/1610.01677


PG0948+534 is currently one of the hottest DA white dwarf stars, and is also one of the most mysterious. Attempts to model the sharp, deep absorption features of this star have been unsuccessful. In these proceedings we describe our analysis of PG0948+534. We perform a line survey of the UV spectrum of PG0948+534, making detections of 300+ absorption features, and identifying four distinct velocity regimes. We find evidence of circumstellar absorption in the profiles of C {\sc iv} and Si {\sc iv}. Using non-local thermodynamic equilibrium model atmospheres, we are able to correctly model the absorption features of the star, providing abundance measurements for C, N, O, and Si for PG0948+534 for the first time. We also revise the effective temperature and gravity for this star using models including these new abundances.

Read this paper on arXiv…

S. Preval and M. Barstow
Fri, 7 Oct 16
20/75

Comments: Six pages, two figures. To appear in the proceedings of the 20th European White Dwarf Workshop held in Warwick, 2016