OY CARINAE REVISITED - DEVELOPMENT OF THE ACCRETION DISK DURING A NORMAL OUTBURST
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1992
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Abstract
We re-analyse Vogt's (1983) unique set of white-light eclipse light curves of the dwarf nova OY Carinae during a normal outburst, employing the maximum-entropy eclipse-mapping technique. These eclipse observations provide snapshots of the accretion disk during quiescence, during the early rising phase of an outburst, and at maximum outburst. The basic evolutionary aspects of the disk structure already presented by Vogt (1983) are placed on a more quantitative basis. In particular, the radial brightness profile and brightness temperature profile of the disk during the rise to outburst maximum are presented and discussed in the light of theoretical outburst models; from the observed stability of the disk radius and from the absence of an increase in the luminosity of the bright spot we conclude that the current observations do not offer support for the mass-transfer instability model. Furthermore, our analysis suggests the development of an extra, uneclipsed component during outburst rise, which contributes up to approximately 15% of the total light at outburst maximum. We argue that this extra component most likely represents luminous material well above the orbital plane, which may indicate the development of a wind.
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ACCRETION, ACCRETION DISKS, STARS, BINARIES, CLOSE, STARS, INDIVIDUAL, OY CARINAE, STARS, NOVAE AND CATACLYSMIC VARIABLES