WZ Sagittae - Time-resolved spectroscopy during quiescence

Abstract

High time resolution spectroscopy has been used to obtain an orbital velocity amplitude for the primary component of the dwarf nova WZ Sagittae, an 82 minute binary, of K1 = 49 + or 5 km/s. The line profiles of H-alpha, some seven months after the December 1978 outburst of WZ Sge, were ideal for radial velocity determinations with the S-wave emission component being weaker than normal, while the system brightness was still above preoutburst levels. The higher orbital velocity yields standard solutions for the system masses of M1 approximately 1.1 solar masses, M2 approximately 0.1 solar masses. Implications of the new K1 value and observed line profile variations for the physical model of WZ Sge are discussed. Relative phasing of the velocity and photometric eclipse does not agree with the canonical hot spot model. Si II absorption lines at 4130 and 3856-3863 A redshifted at a stationary velocity of 270 km/s with respect to the systemic velocity of WZ Sge imply the existence of mass accretion to the system.