DOPPLER TOMOGRAPHY OF THE GAS-STREAM IN SHORT-PERIOD ALGOL BINARIES

Doppler tomography of Halpha difference profiles of four short-period Algol-type binaries has revealed the gas stream due to Roche lobe overflow and disklike structures around the mass gainer. The position of the gas stream in the Doppler tomogram closely follows the predicted free fall path from the inner Langrangian point in the rotating reference frame. In U CrB, U Sge, RS Vul, and beta Per, the disklike structures in the tomograms are asymmetric distributions of gas extending out to several times the synchronous rotation rate of the primary star. These tomograms display the first distinct ''images'' of gas streams in the Algols, and in the entire class of interacting binaries.