Binary Stars among Cataclysmic Variables. V. Photoelectric and Spectroscopic Observations of the Ultra-Short Binary Nova WZ Sagittae.

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Abstract

A new model for recurrent Nova WZ Sagittae is advanced based on approximately 3000 ultraviolet photoelectric observations made at Lowell and at Lick, and several nights' spectroscopic runs with the prime-focus spectrograph of the Hale reflector. A simultaneous photoelectric and spectroscopic run over ' periods (P = 0.05668786 days) on August 4,1962 (U.T.) establishes that the W UMa-type eclipse curves and the radial velocities from the hydrogen emission lines are approximately 90 out of phase. Maximum velocity of recession occurs near principal minimum. The new model attributes this effect to a rapidly receding stream ejected from the dark star toward the primary component. The properties of the radiation field of the white-dwarf primary are derived from tracings of H in absorption and are shown to be consistent with the observed geometrical extent of the line-emitting regions. The best present estimates of the geometrical and dynamical parameters of the system are: = 0. , 2 = 0.03 ®, 2/ 1 = 0.05, R1 = 0.87 x 109cm, x 109cm, a = 3.7 X 1010 cm, where the subscript I refers to the white-dwarf primary. The numbers are rather uncertain, but there is little doubt that the mass ratio is unusually small, though some of the observational details remain poorly explained. However, the mass of the secondary is similar to that of L726-8B, in which case the value of the radius derived from the eclipse data agrees with the radius of L726-8B. The proposed emission of gravitational waves is such that the gain in phase is 1 sec in 12 years. It is likely that mass transfer and mass loss during outbursts of WZ Sge severely mask the period changes resulting from the emission of gravitational waves.

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