LBV 1806-20

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LBV 1806-20
Observation data
Epoch J2000      Equinox J2000
Constellation Sagittarius
Right ascension 18h 08m 40.3s
Declination −20° 24′ 41″
Distance 38.7k[1] ly
(11.8k[1] pc)
Mass 65 + 65[2] M
Radius 150 R
Luminosity ~2 × 106(bolometric)[1][2] L
Temperature 18–36,000 K
Age < 2 × 106 years
Database references

LBV 1806-20 is a candidate luminous blue variable (LBV) and likely binary star located nearly 40,000 light-years from the Sun, towards the center of the Milky Way. It has a total system mass of around 130 solar masses and an estimated variable luminosity of around two million times that of the Sun.

Despite its high luminosity, it is virtually invisible from the Solar System, because less than one billionth of its visible light reaches us, the rest being absorbed by intervening interstellar gas and dust. Although the star is 8th magnitude at the near infrared wavelength of 2 micrometers, it is calculated to be about 35th magnitude at visible wavelengths, which is undetectable. On the basis of its luminosity and spectral type it is suspected of being an LBV, but despite the name the characteristic photometric and spectroscopic variations have not yet been observed so it remains just a candidate.

When first discovered, LBV 1806-20 was considered both the most luminous and most massive star known, challenging our understanding of the formation of massive stars. Recent estimates place it somewhat nearer to Earth, which when combined with its binary nature mean that it is now well within the expected range of parameters for the most luminous stars in the galaxy.


LBV 1806-20 lies at the core of radio nebula G10.0-0.3 and is a component of the star cluster Cl* 1806-20, itself a component of W31, one of the largest H II regions in the Milky Way. Cluster 1806-20 is made up of some highly unusual stars, including at least two carbon-rich Wolf–Rayet stars (WC9d and WCL), two blue hypergiants, and a magnetar (SGR 1806-20).

See also[edit]


  1. ^ a b c Yael Naze; Gregor Rauw; Damien Hutsemekers (2011). "The first X-ray survey of Galactic Luminous Blue Variables". v1. arXiv:1111.6375 [astro-ph.SR]. 
  2. ^ a b Figer, D. F.; Najarro, F.; Kudritzki, R. P. (2004). "The Double-lined Spectrum of LBV 1806-20". The Astrophysical Journal 610 (2): L109. arXiv:astro-ph/0406316. Bibcode:2004ApJ...610L.109F. doi:10.1086/423306.  edit

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