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An Archival Study of HST Observations of Her X-1/HZ Her

Published online by Cambridge University Press:  12 April 2016

F. H. Cheng ,
S. D. Vrtilek  and
J. C. Raymond
F. H. Cheng
Affiliation:
University of Maryland, USA
S. D. Vrtilek
Affiliation:
University of Maryland, USA Harvard-Smithsonian Center for Astrophysics, USA
J. C. Raymond
Affiliation:
Harvard-Smithsonian Center for Astrophysics, USA

Extract

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Her X-1 is an X-ray pulsar with a rotation period of 1.24 s and a binary period of 1.7d (Tananbaum et al. 1972). The 1.7 d variations in optical and ultraviolet flux are attributed to X-ray heating of the companion star and disk (e.g. Howarth & Wilson 1983, hereafter HW83). The system displays a 35 d period, attributed to the effects of a tilted, precessing, accretion disk. Optical and ultraviolet flux variations continue unchanged throughout. This work is motivated by the following reasons:

  1. • The observed IUE spectra have significantly flatter slopes than those predicted by previous models (e.g. HW83).

  2. • The observed strength of the Balmer jump is anomalously low compared to that expected for a normal B star (Anderson et al. 1994).

  3. • HST observations obtained by Anderson et al. (1994) in order to study emission lines have yielded high quality spectra of the continuum emission from HZ Her, enabling for the first time detailed model fitting efforts.

Type
X-Ray Binaries
Information
International Astronomical Union Colloquium , Volume 158: Cataclysmic Variables and Related Objects , 1996 , pp. 381 - 382
Copyright
Copyright © Kluwer 1996

References

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