Complete spectral energy distribution of the hot, helium-rich white dwarf RX J0503.9–2854

Abstract

Context. In the line-of-sight toward the DO-type white dwarf RX J0503.9−2854, the density of the interstellar medium (ISM) is very low, and thus the contamination of the stellar spectrum almost negligible. This allows to identify many metal lines in a wide wavelength range from the extreme ultraviolet to the near infrared. Aims. In previous spectral analyses, many metal lines in the ultraviolet spectrum of RX J0503.9−2854 have been identified. A complete line list of observed and identified lines is presented here. Methods. We compared synthetic spectra that had been calculated from model atmospheres in non-local thermodynamical equilibrium, with observations. Results. In total, we identified 1272 lines (279 of them were newly assigned) in the wavelength range from the extreme ultraviolet to the near infrared. 287 lines remain unidentified. A close inspection of the EUV shows that still no good fit to the observed shape of the stellar continuum flux can be achieved although He, and Ba are included in the stellar atmosphere models. Conclusions. There are two possible reasons for the deviation between observed and synthetic flux in the EUV may have two reasons. Opacities from hitherto unconsidered elements in the model-atmosphere calculationmay be missing, and/or the effective temperature is slightly lower than previously determined.

Metal abundances in hot white dwarfs with signatures of a superionized wind

“…In the FUSE spectrum of HS 0713+3958, we possibly found lines from heavier elements but the spectrum is too noisy for firm detections. By comparison with the DO white dwarf RE 0503−289, which has similar T eff and log g (75 000 K, 7.5) and in which 14 trans-Fe elements were discovered (Hoyer et al 2017), lines from Zn v, Ge v/vi, Se vi, Mo vi, Sn v, and Te vi might be present.…”

(Pre)-white dwarf stars as measuring tools for yields of AGB nucleosynthesis

“…1). Although that does not help constraining AGB yields, the fact that these upper limits lie below the strong enrichment determined in the DO-type WD RE 0503−289 (Hoyer et al 2017), confirms the understanding of stellar wind and diffusion. While diffusion can accumulate s-process elements in the atmosphere of post-AGB stars in the regime of hot WDs, the strong, coupled stellar wind of CSPNe prevents this process.…”

Discovery of two bright DO-type white dwarfs

“…This explain why J2311+2929 still shows some C and J0536+5448 does not. Figure. 4 also shows the locations of the three DO white dwarfs, RE 0503-298, WD 0111+002 and PG 0109+111, studied by Hoyer et al (2017Hoyer et al ( , 2018. These stars are located close to the positions of our two bright DO white dwarfs, therefore it seems likely that J0536+5448 and J2311+2929 display high abundances of trans-iron elements, too.…”