WR 136 is aWolf–Rayet star located in the constellationCygnus. It is in the center of theCrescent Nebula. Its age is estimated to be around 4.7 million years and it is nearing the end of its life. Within a few hundred thousand years, it is expected to explode as asupernova.[8]
According to recent estimations, WR 136 is 600,000 times brighter than theSun, 21 times more massive, and 5.1 times larger. Itssurface temperature is around 70,000kelvins.[4]
WR 136 blew off a shell of material with a mass of around 5 M☉ when it became ared supergiant around 120,000–240,000 years ago and this is still expanding at 80 km/s.[9] Currently, its faststellar wind, ejected from the star at around 3.8 million mph (1,700 km/s[10]), is catching up to the material ejected from the star and shaping it into a shell.Ultraviolet rays emitted from WR 136's hot surface cause the shell to glow.[9]
There is some evidence WR 136 may be abinary star. Its companion would be a low-mass star ofspectral classificationK orM that would complete an orbit around the Wolf-Rayet star each 5.13 days, being the progenitor of alow-mass X-ray binary system.[11]
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^abcdefgSota, A.; Maíz Apellániz, J.; Morrell, N. I.; Barbá, R. H.; Walborn, N. R.; Gamen, R. C.; Arias, J. I.; Alfaro, E. J.; Oskinova, L. M. (2019). "The Galactic WN stars revisited. Impact of Gaia distances on fundamental stellar parameters".Astronomy & Astrophysics.A57: 625.arXiv:1904.04687.Bibcode:2019A&A...625A..57H.doi:10.1051/0004-6361/201834850.S2CID104292503.
^Barbier-Brossat, M.; Petit, M.; Figon, P. (1994). "Third bibliographic catalogue of stellar radial velocities (Text in French)".Astronomy and Astrophysics Supplement Series.108: 603.Bibcode:1994A&AS..108..603B.
^Hamann, W.-R.; Wessolowski, U.; Koesterke, L. (1994). "Non-LTE spectral analyses of Wolf-Rayet stars: The nitrogen spectrum of the WN6 prototype HD 192163 (WR136)".Astronomy and Astrophysics.281: 184.Bibcode:1994A&A...281..184H.ISSN0004-6361.
Bychkov, K. V.; Sitnik, T. G. (2006). "Stratification of optical emission from NGC 6888 as a trace of the interaction between Wolf-Rayet stellar wind and the shell of a red supergiant".Astronomy Letters.32 (6): 406.Bibcode:2006AstL...32..406B.doi:10.1134/S1063773706060041.S2CID123039046.
