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 over flow and disklike structures around the mass gainer. The position of t he gas stream in the Doppler tomogram closely follows the predicted fr ee fall path from the inner Langrangian point in the rotating referenc e frame. In U CrB, U Sge, RS Vul, and beta Per, the disklike structure s in the tomograms are asymmetric distributions of gas extending out t o several times the synchronous rotation rate of the primary star. The se tomograms display the first distinct ''images'' of gas streams in t he Algols, and in the entire class of interacting binaries.