PSR B1259−63

PSR B1259−63 is a pulsar and member of an eclipsing binary star system with the blue O9.5Ve-class star SS 2883. The pair has an eccentric orbit that is inclined to the line of sight from Earth by about 36°, leading to a 40-day-long eclipse each time the pulsar passes behind the star. The pulsar has a period of 47.762 milliseconds and a luminosity of. It emits very high energy gamma rays that vary on a time scale of several days.
The star SS 2883 has about 22.5 solar masses and is 10.4 solar radii in size. The rate of rotation is about 280 km/s at the equator, or 70% of the breakup velocity.