WR 104

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WR 104
Observation data
Epoch 2000      Equinox 2000
Constellation Sagittarius
Right ascension 18h 02m 04.07s[1]
Declination −23° 37′ 41.2″[1]
Spectral type WC9d/B0.5V[3]
Distance 2,300[3] pc
Absolute magnitude (MV) −5.4 (−4.8 + −4.6)[4]
Radius 10[5] R
Luminosity 150,000[5] L
Temperature 40,000[5] K
Other designations
Database references


WR 104 is a binary star system located about 7,500 light years from Earth. The primary is a Wolf-Rayet star and the secondary is a main sequence OB star.

WR 104 is surrounded by a distinctive dusty pinwheel nebula over 200 astronomical units long formed by interaction between the stellar winds of the two stars as they rotate and orbit. The spiral is composed of dust that would normally be prevented from forming by WR 104's intense radiation were it not for the star's companion. The region where the stellar wind from the two massive stars interacts compresses the material enough for the dust to form, and the rotation of the system causes the spiral-shaped pattern.[6] The round appearance of the spiral leads to the conclusion that the system is seen almost pole on, and an almost circular orbital period of 220 days had been assumed from the pinwheel outflow pattern.[7]

WR 104 shows frequent eclipse events as well as other irregular variations in brightness. The undisturbed apparent magnitude is around 12.7, but the star is rarely at that level. The eclipses are believed to be by dust formed from expelled material, not by the companion star.[2] A third star, about 2 magnitudes fainter than the spectroscopic pair at visual wavelengths, has been resolved almost 1" distant.[8]


  1. ^ a b . Bibcode:2003yCat.2246....0C.  Missing or empty |title= (help)
  2. ^ a b Williams, P. M. (2014). "Eclipses and dust formation by WC9 type Wolf-Rayet stars". Monthly Notices of the Royal Astronomical Society 445 (2): 1253–1260. doi:10.1093/mnras/stu1779. ISSN 0035-8711. 
  3. ^ a b Van Der Hucht, K. A. (2001). "The VIIth catalogue of galactic Wolf–Rayet stars". New Astronomy Reviews 45 (3): 135. doi:10.1016/S1387-6473(00)00112-3. 
  4. ^ Williams, P. M.; van der Hucht, K. A. (2000). "Spectroscopy of WC9 Wolf-Rayet stars: a search for companions". Monthly Notices of the Royal Astronomical Society 314 (1): 23–32. doi:10.1046/j.1365-8711.2000.03332.x. ISSN 0035-8711. 
  5. ^ a b c Sander, A.; Hamann, W. -R.; Todt, H. (2012). "The Galactic WC stars". Astronomy & Astrophysics 540: A144. arXiv:1201.6354. Bibcode:2012A&A...540A.144S. doi:10.1051/0004-6361/201117830. 
  6. ^ Tuthill, P. G.; Monnier, J. D.; Danchi, W. C. (1999). "A dusty pinwheel nebula around the massive star WR104". Nature 398 (6727): 487. Bibcode:1999Natur.398..487T. doi:10.1038/19033. 
  8. ^ . Bibcode:2002ASPC..260..407W.  Missing or empty |title= (help)

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