HD 269810

Properties

HD 269810 is classified as an O2 III (f^*) star with a temperature of 52,500 K. The luminosity class of III indicates a star somewhat evolved and expanded compared to the zero-age main sequence. The spectral peculiarity code (f^*) indicates strong Niii emission lines, even stronger Niv emission, and weak Heii emission. The star's radius is 18 R_☉, but because of its high surface temperature it is two million times brighter than the Sun. The high temperature generates a fast stellar wind of 3,750 km/s (2,330 mi/s), shedding over a millionth of the mass of the sun each year. In 1995, HD 269810 was estimated to be 190 times the mass of the Sun and was thought to be the heaviest star known, but its mass estimate is now revised down to be around 130 M_☉.

Stars as massive as HD 269810 with metallicity typical of the Large Magellanic Cloud will maintain near-homogeneous chemical structure due to strong convection and rotational mixing. This produces strong helium and nitrogen surface abundance enhancement even during core hydrogen burning. Their rotation rates will also decrease significantly due to mass loss and envelope inflation, so that gamma-ray bursts are unlikely when this type of star reaches core collapse. They are expected to develop directly into Wolf–Rayet stars, passing through WN, WC, and WO stages before exploding as a type Ic supernova and leaving behind a black hole. The total lifetime would be around 2 million years, showing an O-type spectrum for most of that time before a shorter period with a WR spectrum.