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E.C. Olson (U of IL at Urbana-Champaign), P.B. Etzel (San Diego State Univ.)
We describe results from intermediate-band I(Kron)ybvu photometry and CCD spectroscopy of the long-period Algol eclipsing binary RX Geminorum. The best solution yields a hot-star rotation about 19 times the synchronous rate and a photometric mass ratio about 0.19. Problems with the earlier solution of Hall & Walter are resolved: neither a continuum-emitting 'ring' nor a polar hot spot are required on the hot star. The hot-star radial velocity curve is distorted so a reliable spectroscopic mass ratio cannot be found. Binary parameters are based on new observations of the well-defined cool-star velocity curve and the photometric mass ratio. RX Gem is presently a deeply but partially eclipsing semidetached binary and the usual caveats apply to our solution. There are suggestions that significant orbital change has occurred during the 20th century. A possible explanation invokes perturbations by an unseen third body. We found a significant departure from circular rotation in accretion disk H\alpha emission, traceable to stream impact on the disk. Sudden brightenings of one emission lobe originate in the stream impact region of the disk. Thus, disk H\alpha emission variations probably result from mass-transfer bursts. This work was partially supported by NSF grant AST-9417035.