The orbit of GK Persei

Abstract

New spectroscopic observations of the old nova GK Per reveal the orbital period to be 1.996803 + or - 0.000007 days. The orbit is circular and the late-type component has a semiamplitude of 124 + or - 2 km/s. The hydrogen emission lines show a velocity variation in antiphase with the absorption lines with a semiamplitude of 34 + or - 5 km/s. The most probable masses are 0.25 solar mass for the K star and 0.9 solar mass for the white dwarf. The K star has obviously lost a lot of mass and is continuing to do so. An effort should be made to obtain photometry at the predicted times of occultation to see whether the system is eclipsing in order to further define the parameters of the system.