Orbital Solutions for WZ Sagittae During Quiescence

Abstract

WZ Sagittae was one of the first cataclysmic variables shown to be a binary system (Kraft 1961) from spectroscopic observations. Krzeminski (1962) found that WZ Sge was an eclipsing binary with an 81 min 38 s orbital period. Krzeminski and Kraft (1964, hereafter KK) in the first of many comprehensive analyses of the WZ Sge system to appear in the literature stated “a lower limit to certain detection of orbital velocity changes for the double emission feature is 2K = 75 km s^-1.” Interpreted as an upper limit to Kj of 37.5 kms 1 this fundamental result has remained untested for two decades, although interpretations and observations of WZ Sge have led to a vast literature. Despite the lack of a well determined orbital velocity, WZ Sge is one of the most thoroughly studied cataclysmic variables. The photometric properties during quiescence have been thoroughly studied and discussed (Robinson, et al.1978; Fabian, et al.1978; Ritter and Schroder 1979), although a consensus on model parameters has remained elusive. Results of spectroscopic observations are presented here which were obtained seven months after the 1978 outburst of WZ Sge. The primary result is a substantial upward revision for the orbital velocity amplitude of the primary component. The higher velocity allows solutions for the component masses in which the secondary (M₂. ~1 M₀) is resident on the zero-age main sequence while the white dwarf mass remains under the Chandrasekhar limit (M₁ ~1.1 M_⊙).

The National Center for Atmospheric Research is sponsored by the National Science Foundation.