Epoch J2000.0 Equinox J2000.0
|Right ascension||5h 38m 42.43s|
|Declination||−69° 06′ 02.2″|
|Apparent magnitude (V)||12.77|
|B−V color index||+0.01|
|Luminosity||≈ (8.7)×106 L☉|
|Temperature||53,000 ± 3,000 K|
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. It is also the most luminous star known at 8,700,000 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. The mass of the star was determined by Paul Crowther et al. (2010).
News of the star's discovery was published in July 2010. A team of British astronomers led by Paul Crowther, professor of astrophysics at the University of Sheffield, used European Southern Observatory's Very Large Telescope (VLT) in Chile, as well as data from the Hubble Space Telescope, to study two star clusters, NGC 3603 and R136a. R136a was once thought to be a supermassive object with 1000–3000 solar masses. R136a's nature was resolved by holographic speckle interferometry and found to be a dense star cluster. The team found several stars with surface temperatures exceeding 40,000–56,000 K, more than seven times that of the Sun, and which are several million times brighter. At least three of the stars weigh in at about 150 solar masses.
Physical characteristics 
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 solar masses and has lost 50 solar masses over the past million years. However, current theories suggest that no stars can be born above 150 solar masses but instead supermassive stars like this one formed through mergers of multiple stars.
Stars between about 8 and 150 solar masses 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 solar masses, astronomers suspect that such an enormous star will perish as a hypernova, a stellar explosion with an energy of over 100 supernovae (1046 joules). The star may also die prematurely long before its core could collapse naturally from lack of fuel as a "pair-instability supernova". Hydrogen-fusing cores should create large numbers of electron–positron pairs, which drop the thermal pressure present within the star to the point a partial collapse occurs. If R136a1 underwent such an explosion it would fail to leave behind a black hole and instead the dozen solar masses of iron within its core would be blown out into the interstellar medium as a supernova remnant.
See also 
|Wikinews has related news: Astronomers discover largest star on record|
- List of most massive stars
- List of most luminous stars
- Orders of magnitude (length)
- List of largest known stars
- Lynx Arc
- RMC 136a1 – Star in Cluster, database entry, SIMBAD.
- Crowther, Paul A.; Schnurr, Olivier; Hirschi, Raphael; Yusof, Norhasliza; Parker, Richard J.; Goodwin, Simon P.; Kassim, Hasan Abu (2010). "The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150 M☉ stellar mass limit". Monthly Notices of the Royal Astronomical Society 408 (2): 731–751. arXiv:1007.3284. Bibcode:2010MNRAS.408..731C. doi:10.1111/j.1365-2966.2010.17167.x.
- "A 300 Solar Mass Star Uncovered". ESO Press Release. 2010-07-21.
- PDF (R136a and the Central Object in the Giant HII Region NGC 3603 Resolved by Holographic Speckle Interferometry).
- Banerjee, Sambaran; Kroupa, Pavel; Oh, Seungkyung (2012). The emergence of super-canonical stars in R136-type star-burst clusters. arXiv:1208.0826. Bibcode:2012arXiv1208.0826B.