The old-novae GK Per. II. Optical outbursts.

The paper reports the results of photographic and spectroscopic observations of the old-nova GK Per (1901) carried out in February-April 1981 when the nova underwent a particularly large optical outburst. The nova behavior during the outbursts is explained by an increase in the mass transfer rate from the late-type secondary onto the primary. The observed luminosity variation corresponds to an accretion rate changing from 10 to the 18th to 10 to the 20th g/s and to an increase in temperature, including the maximum temperature near the inner edge, by a factor of three.