Epoch J2000.0 Equinox J2000.0
|Right ascension||5h 38m 42.43s|
|Declination||−69° 06′ 02.2″|
|Apparent magnitude (V)||12.28|
|B−V color index||+0.17|
|Absolute magnitude (MV)||-7.10|
BAT99 108, RMC 136a1, [HSH95] 3, [WO84] 1b, Cl* NGC 2070 MH 498, [CHH92] 1, [P93] 954.
R136a1 is a Wolf–Rayet star and the most massive star known. It is an estimated 265 solar masses (M☉). It is also the most luminous star known at 7,400,000 times the luminosity of the Sun. It is a member of R136, a super star cluster near the center of the 30 Doradus complex (also known as the Tarantula Nebula), in the Large Magellanic Cloud.
R136a was first resolved using speckle interferometry in the early 1980's. R136a1 was marginally the brightest of eight components found within 1 arc-second at the centre of the R136 cluster. Previous estimates that the brightness of the central region would require as many as 30 hot O class stars within half a parsec at the centre of the cluster had led to speculation that a star several thousand times the mass of the sun was the more likely explanation. Instead it was eventually found that R136 consisted of a few extremely luminous stars accompanied by a larger number of hot O stars.
R136a1 is a Wolf–Rayet star with surface temperature over 50,000 K . Like other stars that are close to the Eddington limit, R136a1 has been shedding a large fraction of its initial mass through a continuous stellar wind. It is estimated that at its birth the star held 320 M☉ and has lost 50 M☉ over the past million years. However, current theories suggest that no stars can be born above 150 M☉ but instead supermassive stars like this one formed through mergers of multiple stars.
Stars between about 8 and 150 M☉ explode at the end of their lives as supernovae, leaving behind neutron stars or black holes. Having established the existence of stars between 150 and 300 M☉, astronomers suspect that such an enormous star will perish as a hypernova, a stellar explosion with an energy of over 100 supernovae (1046 joules).
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