Institut für Astronomie und Astrophysik Abteilung Astronomie Sand 1, D-72076 Tübingen, Germany

Preprint 01/16

Stellar laboratories. VII. New Kr IV - VII oscillator strengths and an improved spectral analysis of the hot, hydrogen-deficient DO-type white dwarf RE0503−289

T. Rauch (1), P. Quinet (2 and 3), D. Hoyer (1), K. Werner (1), P. Richter (4), J. W. Kruk (5), M. Demleitner (6)

(1) Institute for Astronomy and Astrophysics, Eberhard Karls University, Tuebingen, Germany
(2) Physique Atomique et Astrophysique, Universite de Mons - UMONS, Belgium
(3) IPNAS, Universite de Liege, Liege, Belgium
(4) Institute of Physics and Astronomy, University of Potsdam, Golm, Germany
(5) NASA Goddard Space Flight Center, Greenbelt, USA
(6) Astronomisches Rechen-Institut (ARI), Centre for Astronomy of Heidelberg University, Heidelberg, Germany

To be published in: A&A

Abstract. For the spectral analysis of high-resolution and high-signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation.
New of Kr IV - VII oscillator strengths for a large number of lines allow to construct more detailed model atoms for our NLTE model-atmosphere calculations. This enables us to search for additional Kr lines in observed spectra and to improve Kr abundance determinations.
We calculated Kr IV - VII oscillator strengths to consider radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Kr lines exhibited in high-resolution and high-S/N ultraviolet (UV) observations of the hot white dwarf RE 0503-289.
We reanalyzed the effective temperature and surface gravity and determined T_eff = 70 000 ± 2000 K and log (g / cm/s**2) = 7.5 ± 0.1. We newly identified ten Kr V lines and one Kr VI line in the spectrum of RE 0503-289. We measured a Kr abundance of -3.3 ± 0.3 (logarithmic mass fraction). We discovered that the interstellar absorption toward RE 0503-289 has a multi-velocity structure within a radial-velocity interval of -40 km/s < vrad < +18 km/s.
Reliable measurements and calculations of atomic data are a prerequisite for state-of-the-art NLTE stellar-atmosphere modeling. Observed Kr V - VII line profiles in the UV spectrum of the white dwarf RE 0503-289 were simultaneously well reproduced with our newly calculated oscillator strengths.
 
Key words: atomic data, line: identification, stars: abundances, stars: individual: RE0503-289, stars: individual: RE0457-281, virtual observatory tools

Preprint (1,08 Mb PDF file including figures)

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