BAT99-123, also known as Brey 93, is a rare WO-type (oxygen sequence) Wolf–Rayet star located in the Large Magellanic Cloud, about 160,000 light years away in Dorado. BAT99-123 was the first WO star discovered in the LMC, and only 3 are known to exist in the galaxy, the other two being LH 41-1042 and LMC195-1.
BAT99-123 was first discovered in 1970, and identified as a star with strong OVI emission in 1971, alongside other WO stars like WR 102, WR 142 and SMC AB8.[4] Most stars with strong OVI emission known at the time were central stars of planetary nebulae.
Properties
Analysis of BAT99-123's spectrum reveals a surface temperature of 170,000 K. Assuming a distance of 50.12 kpc, or about 163,500 light years, BAT99-123's luminosity is about 158,500 L☉, corresponding to a radius of 0.47 R☉. BAT99-123's strong stellar wind, which has a very high terminal velocity of 3300 km/s, causes it to lose 10-5.14 M☉ (about 7.24×10−6M☉) a year.[3]
WO-type Wolf-Rayet stars are very very close to the end of their lives. BAT99-123 is predicted to explode in a type Ic supernova in about 7,000 years. By then, it's predicted to have a mass of 7.7 M☉, much lower than its initial mass which was likely a few dozen solar masses.[3] It likely has a similar mass right now as its stellar wind will not change the mass much in this timescale.