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Line Band Profiles in the Spectra of Cool Magnetic Helium-Rich White Dwarfs

Published online by Cambridge University Press:  12 April 2016

I. Bues
I. Bues*
Affiliation:
Remeis Sternwarte Bamberg Institut für Astronomie der Universität Erlangen Nürnberg, F.R.G.

Extract

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For white dwarfs with effective temperatures smaller than 12000 K, the percentage of objects with a helium-rich atmosphere increases compared to the hydrogen-rich sequence. The carbon abundance, which can be determined from line and band strengths (Bues, 1973; Koester et al., 1982), varies by more than a factor of 1000 within this class. Moreover, for the subclass of white dwarfs with strong magnetic fields, the abundance ratio of H/He differs from that of the DB and DA sequences. The hot star Feige 7, analyzed by Liebert et al. (1977), shows lines of hydrogen and helium at a comparable strength for a moderately strong field of 103 Tesla. If there is any chance of finding white dwarfs which are descendants of hot, non-degenerate helium stars with rotation and magnetic fields, then it should be within these objects of mixed composition.

Type
VII Related Objects
Information
International Astronomical Union Colloquium , Volume 87: Hydrogen Deficient Stars and Related Objects , 1985 , pp. 391 - 395
Copyright
Copyright © Reidel 1986

References

Bues, I.: 1973, Astron. Astrophys. 28, 181 Google Scholar
Koester, D., Weidemann, V., Zeidler-K.T., E.-M.: 1982, Astron. Astrophys. 116, 147 Google Scholar
Landstreet, J.D.: 1982, private communicationGoogle Scholar
Liebert, J.: 1976, P.A.S.P. 88, 490 Google Scholar
Liebert, J., Angel, J.R.P., Stockman, H.S., Spinrad, H., Beaver, E.A: 1977, Astrophys. J. 214, 457 CrossRefGoogle Scholar
Rupprecht, G.: 1983, Ph.D. Thesis, Universität Erlangen-Nürnberg Google Scholar