WR 136

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WR 136
WR136 in NGC6888.jpg
WR 136
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus
Right ascension 20h 12m 06.5421s
Declination +38° 21′ 17.779″
Apparent magnitude (V) 7.48
Spectral type WN6(h)
U−B color index  ?
B−V color index 0.009 ± 0.047
Variable type None
Radial velocity (Rv) −21.6 km/s
Proper motion (μ) RA: −7.54 mas/yr
Dec.: −7.38 mas/yr
Parallax (π) 0.61 ± 0.63 mas
Distance approx. 5,000 ly
(approx. 2,000 pc)
Absolute magnitude (MV) −4.7[1]
Mass 15[1] M
Radius 3.34[1] R
Luminosity 105.4[1] L
Temperature 70,800[1] K
Metallicity ?
Rotation ?
Age 4.5 million years
Other designations
V* V1770 Cyg, AG+38 1977, GSC 03151-01765, BD+37 3821, HD 192163, HIC 99546, HIP 99546, GC 28056, SAO 69592.
Database references

WR 136 is a Wolf–Rayet star located in the constellation Cygnus. It is in the center of the Crescent Nebula. Its age is estimated to be around 4.5 million years[2] and it is nearing the end of its life. Within the next few million years, it is expected to explode as a supernova.[3]


According to recent estimations, WR 136 is 250,000 times brighter than our Sun, 15 times more massive, and 3.3 times larger. Its surface temperature is around 70,000° Kelvin.[1]

WR 136 blew off a shell of material when it became a red supergiant around 250,000 years ago with a mass of around 30 solar masses.[2] Currently, its fast stellar wind, ejected from the star at around 3.8 million mph (6.1 million km/h), is catching up to the material ejected from the star and shaping it into a shell. UV rays emitted from WR 136's hot surface cause the shell to glow.[4]

There's certain evidence WR 136 may be a binary star. Its companion would be a low-mass star of spectral classification K or M that would complete an orbit around the Wolf-Rayet star each 5.13 days, being the system the progenitor of a low-mass X-ray binary.[5]

See also[edit]


  1. ^ a b c d e f Hamann, W.-R.; Gräfener, G.; Liermann, A. "The Galactic WN stars. Spectral analyses with line-blanketed model atmospheres versus stellar evolution models with and without rotation". Astronomy and Astrophysics 457 (3). pp. 1015–1013. Bibcode:2006A&A...457.1015H. Retrieved 17 July 2013. 
  2. ^ a b "WR 136". 
  3. ^ "Crescent Nebula Close-up (NGC 6888)". 
  4. ^ Moore, Brian D.; Hester, Jeff; Scowen, Paul; Dufour, Reginald (13 July 2000). "Hubble Watches Star Tear Apart its Neighborhood". NASA. 
  5. ^ Rustamov, D. N.; Cherepashchuk, A. M. "The Wolf-Rayet star HD 192163 as a possible evolutionary progenitor of a low-mass X-ray binary". Astronomy Reports 55 (4). pp. 347–358. Bibcode:2011ARep...55..347R. Retrieved 17 July 2013.