THE EVOLUTIONARY STATUS OF BETA PER

Algol (beta Per) is a very well-known eclipsing close binary system wh ich was discovered by Goodricke in 1782. Algol has been an intensively studied object ever since, and it has been detected over a very broad range of wavelengths from radio to X-ray. From observations, orbital and physical parameters for Algol have been determined moderately accu rately. However, there does not exist an exact evolutionary model whic h, starting from some initial conditions (period, mass ratio, primary mass), reproduces the present parameters of the system. In this paper, we therefore examine the evolutionary status of beta Per (Algol). We discuss the system from a non-conservative point of view, concerning m ass transfer, and consider mass and angular momentum losses from the s ystem via a stellar wind. We compare the C abundance determination fro m theoretical models with values known from observational analysis, an d construct a theoretical model which agrees reasonably well with the observed one. The computed parameters lie well inside the observationa l error. During evolution, beta per loses about 15 per cent of its ini tial total mass (DELTAM approximately 0.81 M.) and 30 per cent of its initial total angular momentum.