The question of the nature of the ultraviolet and X-ray radiation field of cataclysmic binaries is addressed. The spectrum and luminosity of this radiation are important in determining the mass transfer rate and energy budget of the system and in studies of the ejecta surrounding novae. In many systems, the soft X-ray luminosity is ~ 102-104 times weaker than predicted by simple accretion models. We discuss several possible solutions to this discrepancy. The most likely are either that the optical luminosity of a typical old nova is produced partly by reprocessed ultraviolet light from the white dwarf, or that the boundary layer, where accreted matter settles onto the white dwarf is both larger and more complicated than predicted by existing accretion disk models. The solution to this problem is of fundamental importance to accretion disk theory and will have implications for the study of most aspects of these systems, including models of the nova outburst itself.

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Published in The Astrophysical Journal Letters, v. 262, no. 2, p. L53-L58.

© 1982. The American Astronomical Society. All rights reserved.

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