Increase in the orbital period of AM Canum Venaticorum.

Photometry of the cataclysmic binary AM Canum Venaticorum (= HZ 29) reveals a remarkable increase in its 17.5-minute orbital period. The period change is likely to be due to mass transfer at a rate of 3 x 10 to the -7th solar masses/year. At this rate, the degenerate secondary will be cannibalized in approximately 100,000 years. The mechanism for the mass transfer is unknown, but it cannot be gravitational radiation at the rate given by general relativity. If extensive angular momentum loss from the system occurs, a possible mechanism is the expansion of the degenerate secondary due to mass loss.