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Observation data
Epoch J2000      Equinox J2000
Constellation Dorado
Right ascension 05h 22m 59.809s[1]
Declination −68° 01′ 46.57″[1]
Apparent magnitude (V) 11.46[2]
Spectral type LBV
U−B color index −0.92[2]
B−V color index +0.25[2]
Variable type LBV[3]
Radial velocity (Rv) 293 ± 16.2[4] km/s
Proper motion (μ) RA: 3.4 ± 2.5[1] mas/yr
Dec.: −0.4 ± 2.3[1] mas/yr
Distance 50,000 pc
Absolute magnitude (MV) −8.48[5]
Mass 103[5] M
Radius 74.8[5] R
Luminosity 3.2 × 106[5] L
Temperature 28,000[5] K
Other designations
HD 269445, BAT99 33, AAVSO 0523-68, 2MASS J05225978-6801466
Database references

R99 (HD 269445) is a star in the Large Magellanic Cloud in the constellation Dorado. It is classified as a luminous blue variable and is one of the most luminous stars known.

R99 has a peculiar spectrum that has been described as OBf:pe,[6] "unclassifiable", peculiar WN10, "similar to the unusual LBV HD 5980",[7] "unique", and Ofpe/WN9.[8] It shows brightness variations of about 0.3 magnitude over a period of decades, and smaller amplitudes with the strongest periods at two and ten days. The colour also varies, with the star being bluer at minimum light.[9] It has been classified as a Luminous Blue Variable on account of the variability and spectrum, although it has never been observed in outburst.[3]


  1. ^ a b c d Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27. Bibcode:2000A&A...355L..27H. 
  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 Van Genderen, A. M. (2001). "S Doradus variables in the Galaxy and the Magellanic Clouds". Astronomy and Astrophysics 366 (2): 508. Bibcode:2001A&A...366..508V. doi:10.1051/0004-6361:20000022. 
  4. ^ Schnurr, O.; Moffat, A. F. J.; St-Louis, N.; Morrell, N. I.; Guerrero, M. A. (2008). "A spectroscopic survey of WNL stars in the Large Magellanic Cloud: General properties and binary status". Monthly Notices of the Royal Astronomical Society 389 (2): 806. Bibcode:2008MNRAS.389..806S. doi:10.1111/j.1365-2966.2008.13584.x. 
  5. ^ 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. arXiv:1401.5474. Bibcode:2014A&A...565A..27H. doi:10.1051/0004-6361/201322696. 
  6. ^ Walborn, N. R. (1977). "Spectral classification of O and B0 supergiants in the Magellanic Clouds". Astrophysical Journal 215: 53. Bibcode:1977ApJ...215...53W. doi:10.1086/155334. 
  7. ^ Crowther, P. A.; Smith, L. J. (1997). "Fundamental parameters of Wolf-Rayet stars. VI. Large Magellanic Cloud WNL stars". Astronomy and Astrophysics 320: 500. Bibcode:1997A&A...320..500C. 
  8. ^ Bohannan, Bruce; Walborn, Nolan R. (1989). "The Ofpe/WN9 class in the Large Magellanic Cloud". Astronomical Society of the Pacific 101: 520. Bibcode:1989PASP..101..520B. doi:10.1086/132463. 
  9. ^ Van Genderen, A. M.; Sterken, C.; De Groot, M.; Reijns, R. A. (1998). "Light variations of massive stars (alpha Cyg variables). XV. The LMC supergiants R99 (LBV), R103, R123 (LBV) and R128". Astronomy and Astrophysics 332: 857. Bibcode:1998A&A...332..857V.