ABSTRACT
The orbit of the peculiar interacting F8 + B binary system is established on the basis of 93 radial-velocity measurements mostly made photoelectrically. The period is 140.78 days, the velocity amplitude is 70 km/s, and the orbit has a small but nevertheless significant eccentricity. The mass function of 5 solar masses is extraordinarily large and probably indicates that the F-type component is the secondary in terms of mass. Optical spectroscopy in the red region reveals strong and variable H-alpha emission, forbidden N II emission at the gamma-velocity of the system, and N I and Na I absorption of circumstellar origin.