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Detection of Heavy Elements in the EUVE Spectrum of a Hot White Dwarf

Published online by Cambridge University Press:  12 April 2016

S. Jordan ,
D. Koester  and
D. Finley
S. Jordan
Affiliation:
Institut für Astronomie und Astrophysik, Universität Kiel, D-24098 Kiel, Germany
D. Koester
Affiliation:
Institut für Astronomie und Astrophysik, Universität Kiel, D-24098 Kiel, Germany
D. Finley
Affiliation:
Center for EUV Astrophysics, 2150 Kittredge Street, University of California, Berkeley, CA 94720-5030, USA

Abstract

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Observations with the ROSAT satellite have already indicated that metal absorbers must be present in the atmosphere of the hot DA white dwarf PG 1234+482. This is now confirmed by strong absorption features found in the short and medium wavelength EUVE spectrum of the star. With fully blanked model atmospheres, taking into account several million lines of heavy elements, we could attribute the strongest features to absorption by FeVI and FeVII. Since the spectrum has not been dithered during the observation other elements could not be identified with the same level of confidence, but upper limits could be determined. These are in general lower than predicted by models, which attempt to explain the presence of the metals by theoretical calculations of radiative forces in hot DA white dwarf atmospheres.

Type
IV. White Dwarf Structure/Evolution
Information
International Astronomical Union Colloquium , Volume 152: Astrophysics in the Extreme Ultraviolet , 1996 , pp. 235 - 240
Copyright
Copyright © Kluwer 1996

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