Stellar laboratories. V. The Xe vi ultraviolet spectrum and the xenon abundance in the hot DO-type white dwarf RE 0503-289

Abstract

Context. For the spectral analysis of spectra of hot stars with a high resolution and high signal-to-noise ratio (S/N), advanced non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that are used for their calculation.
Aims: Reliable Xe vi oscillator strengths are used to identify Xe lines in the ultraviolet spectrum of the DO-type white dwarf RE 0503-289 and to determine its photospheric Xe abundance.
Methods: We publish newly calculated oscillator strengths that are based on a recently measured Xe vi laboratory line spectrum. These strengths were used to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models to analyze Xe vi lines exhibited in high-resolution and high S/N UV observations of RE 0503-289.
Results: We identify three hitherto unknown Xe vi lines in the ultraviolet spectrum of RE 0503-289 and confirm the previously measured photospheric Xe abundance of this white dwarf (log Xe = -4.2 ± 0.6 by mass).
Conclusions: Reliable measurements and calculations of atomic data are prerequisite for stellar-atmosphere modeling. Observed Xe vi line profiles in the ultraviolet spectrum of the white dwarf RE 0503-289 were well reproduced with the newly calculated Xe vi oscillator strengths.

Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer.Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26666.