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[1]
Declination +38° 21′ 17.779″[1]
Apparent magnitude (V) 7.50[2]
Spectral type WN6(h)-s[3]
U−B color index -0.37[2]
B−V color index 0.01[2]
Variable type None
Radial velocity (Rv) −21.6[4] km/s
Proper motion (μ) RA: −7.54[1] mas/yr
Dec.: −7.38[1] mas/yr
Parallax (π) 1.38 ± 0.46[1] mas
Distance approx. 2,400 ly
(approx. 700 pc)
Absolute magnitude (MV) −4.7[3]
Mass 15[3] M
Radius 3.34[3] R
Luminosity 260,000[3] L
Temperature 70,800[3] K
Rotation 37[5]
Age 4.7[6] Myr
Other designations
V1770 Cyg, AG+38 1977, GSC 03151-01765, BD+37 3821, HD 192163, 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 4.7 million years and it is nearing the end of its life. Within the a few hundred thousand years, it is expected to explode as a supernova.[6]


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.[3]

WR 136 blew off a shell of material when it became a red supergiant around 120,000-240,000 years ago with a mass of around 5 M and this is still expanding at 80 km/s.[7] Currently, its fast stellar wind, ejected from the star at around 3.8 million mph (1,700 km/s[8]), 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.[7]

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.[9]


  1. ^ a b c d e Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. 
  2. ^ a b c Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues 2237: 0. Bibcode:2002yCat.2237....0D. 
  3. ^ a b c d e f g Hamann, W.-R.; Gräfener, G.; Liermann, A. (2006). "The Galactic WN stars. Spectral analyses with line-blanketed model atmospheres versus stellar evolution models with and without rotation". Astronomy and Astrophysics 457 (3): 1015. Bibcode:2006A&A...457.1015H. doi:10.1051/0004-6361:20065052. 
  4. ^ Barbier-Brossat, M.; Petit, M.; Figon, P. (1994). "Third bibliographic catalogue of stellar radial velocities (Text in French)". Astronomy and Astrophysics Suppl. 108 108: 603. Bibcode:1994A&AS..108..603B. 
  5. ^ Gräfener, G.; Vink, J. S.; Harries, T. J.; Langer, N. (2012). "Rotating Wolf-Rayet stars in a post RSG/LBV phase". Astronomy & Astrophysics 547: A83. Bibcode:2012A&A...547A..83G. doi:10.1051/0004-6361/201118664. 
  6. ^ a b Moore, Brian D.; Hester, J. Jeff; Scowen, Paul A. (2000). "[ITAL]HUBBLE SPACE TELESCOPE[/ITAL][ITAL]Hubble Space Telescope[/ITAL] Observations of the Wolf-Rayet Nebula NGC 6888". The Astronomical Journal 119 (6): 2991. Bibcode:2000AJ....119.2991M. doi:10.1086/301389. 
  7. ^ a b Mesa-Delgado, A.; Esteban, C.; García-Rojas, J.; Reyes-Pérez, J.; Morisset, C.; Bresolin, F. (2014). "The Trace of the CNO Cycle in the Ring Nebula NGC 6888". The Astrophysical Journal 785 (2): 100. Bibcode:2014ApJ...785..100M. doi:10.1088/0004-637X/785/2/100. 
  8. ^ 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 (ISSN 0004-6361) 281: 184. Bibcode:1994A&A...281..184H. 
  9. ^ Rustamov, D. N.; Cherepashchuk, A. M. (2011). "The Wolf-Rayet star HD 192163 as a possible evolutionary progenitor of a low-mass X-ray binary". Astronomy Reports 55 (4): 347–358. Bibcode:2011ARep...55..347R. doi:10.1134/S1063772911010069. Retrieved 17 July 2013. 

Further reading[edit]

  • 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. 

External links[edit]