Published online by Cambridge University Press: 14 August 2015
An observational study of the Hα feature in Algol type binary systems has revealed the presence of emission in nearly all systems with periods greater than 6 days. The disks which produce this emission are generally thin and can extend out to 90% of the Roche surface of the primary star. If emission is found in the systems of shorter period, it tends to be transient, lasting only a few orbital cycles. In several systems, there is evidence of mass loss from the vicinity of the primary at phase 0.5.