Abstract
A simple method to obtain mass transfer rates in cataclysmic variables is discussed. The temperature T(R) of a steady accretion disc varies as R-3/4, leading to a connection between the accretion rate, the external radius Re and the mean temperature of the disc, M ∝ Re3 Tm4. We find that if the disc size is a roughly constant fraction of the binary separation then Re ∝ P2/3 and < ∝ Tm4 P2. We argue from theoretical and observational reasons that there is no correlation between Tm and P, leading to the conclusion that M ∝ P2. Since the radius of the secondary star is a function of the orbital period, we find that the mass transfer is directly proportional to the surface area of the companion star: M ∝ A8. We use emission lines and photometry to estimate Tm and to calculate mass transfer rates for a large sample of cataclysmic variables, and compare the results with other authors.
