R136a1

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R136a1
The young cluster R136.jpg
R136a1 resolved at the center, with R136a2 close by, R136a3 below right, and R136b to the left.
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Dorado
Right ascension 5h 38m 42.43s
Declination −69° 06′ 02.2″
Apparent magnitude (V) 12.28[1]
Characteristics
Spectral type WN5h[2]
B−V color index +0.17[1]
Astrometry
Distance 165,000 ly
Absolute magnitude (MV) -7.10[3]
Details
Mass 265+80
−35
[2] M
Radius 28.8[3] R
Luminosity 7.4×106[3] L
Temperature 56,000[3] K
Age ~1.7[2] Myr
Other designations
BAT99 108, RMC 136a1, [HSH95] 3, [WO84] 1b, Cl* NGC 2070 MH 498, [CHH92] 1, [P93] 954.
Database references
SIMBAD data

R136a1 is a Wolf–Rayet star and the most massive star known. It is an estimated 265 solar masses (M).[2] It is also the most luminous star known at 7,400,000 times the luminosity of the Sun.[3] 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.[2]

Discovery[edit]

Zooming in from the Tarantula Nebula to the R136 cluster, with R136a1/2/3 visible as the barely resolved knot at bottom right. The brightest star just to the left of the cluster core is R136c, another extreme massive WN5h star.

R136a was first resolved using speckle interferometry in the early 1980s.[4] 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[5] had led to speculation that a star several thousand times the mass of the sun was the more likely explanation.[6] Instead it was eventually found that R136 consisted of a few extremely luminous stars accompanied by a larger number of hot O stars.[1]

Physical characteristics[edit]

Left to right: a red dwarf, the Sun, a blue dwarf, and R136a1. R136a1 is not the largest known star in terms of radius or volume, only in mass and luminosity.

R136a1 is a Wolf–Rayet star with surface temperature over 50,000 K .[2] 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.[2] 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.[7]

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).[citation needed]

See also[edit]

References[edit]

  1. ^ a b c Doran, E. I.; Crowther, P. A.; de Koter, A.; Evans, C. J.; McEvoy, C.; Walborn, N. R.; Bastian, N.; Bestenlehner, J. M. et al. (2013). "The VLT-FLAMES Tarantula Survey - XI. A census of the hot luminous stars and their feedback in 30 Doradus". arXiv:1308.3412v1 [astro-ph.SR].
  2. ^ a b c d e f g Crowther, P. A.; Schnurr, O.; Hirschi, R.; Yusof, N.; Parker, R. J.; Goodwin, S. P.; Kassim, H. A. (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. arXiv:1007.3284. Bibcode:2010MNRAS.408..731C. doi:10.1111/j.1365-2966.2010.17167.x.  edit
  3. ^ a b c d e Hainich, R.; Rühling, U.; Todt, H.; Oskinova, L. M.; Liermann, A.; Gräfener, G.; Foellmi, C.; Schnurr, O.; Hamann, W. -R. (2014). "The Wolf-Rayet stars in the Large Magellanic Cloud". Astronomy & Astrophysics 565: A27. doi:10.1051/0004-6361/201322696.  edit
  4. ^ Weigelt, G.; Baier, G. (1985). "R136a in the 30 Doradus nebula resolved by holographic speckle interferometry". Astronomy and Astrophysics (ISSN 0004-6361) 150: L18. Bibcode:1985A&A...150L..18W. 
  5. ^ Moffat, A. F. J.; Seggewiss, W. (1983). "R 136 - Supermassive star or dense core of a star cluster?". Astronomy and Astrophysics (ISSN 0004-6361) 125: 83. Bibcode:1983A&A...125...83M. 
  6. ^ Cassinelli, J. P.; Mathis, J. S.; Savage, B. D. (1981). "Central Object of the 30 Doradus Nebula, a Supermassive Star". Science 212 (4502): 1497. doi:10.1126/science.212.4502.1497.  edit
  7. ^ Oh, Sambaran; Kroupa, Pavel; Oh, Seungkyung (2012). "The emergence of super-canonical stars in R136-type star-burst clusters". Monthly Notices of the Royal Astronomical Society 1208 (2): 826. arXiv:1208.0826. Bibcode:2012MNRAS.426.1416B. doi:10.1111/j.1365-2966.2012.21672.x. 

Coordinates: Sky map 05h 38m 42.43s, −69° 06′ 02.2″