LBV 1806-20

Starbox begin
name=LBV 1806-20 Starbox observe
epoch=J2000
ra=18^h 08^m 40.3^s
dec=-20° 24′ 41″
constell=Sagittarius Starbox detail
mass=130-200
radius=150
luminosity=2-40 × 10⁶(bolometric)
temperature=18-36,000
metal=?
rotation=?
age=< 2 &times; 10⁶

LBV 1806-20 is a luminous blue variable or possible binary star located 30,000&ndash;49,000 light-years from the Sun, towards the center of the galaxy. It has a total system mass of 130&ndash;150 Solar masses and an estimated variable luminosity of up to 5 million times that of the Sun, [cite web | author = Aaron Hoover
date = 2004-01-05 | url = http://www.napa.ufl.edu/2004news/bigbrightstar.htm | title = Star may be biggest, brightest yet observed | publisher = HubbleSite | language = English | accessdate = 2006-06-08 ] making it comparably luminous to Eta Carinae or the Pistol Star, contenders for the most luminous known star (all of which are luminous blue variables).

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.

Formation theory

Current star formation theories tell us that a star can have at most about 120 Solar masses, but this star has been measured to have at least 130 solar masses. Some even give the star 150 to 200 solar masses. [Cite journal | author=Eikenberry, S.S.; Matthews, K; LaVine, J.L.; Garske, M.A.; Mu, D.; Jackson, M.A.; Patel, S.G.; Barry, D.J.; Colonno, M.R.; Houck, J. R.; Wilson, J.C; Corbel, S.; Smith, J.D. | title=Infrared Observations of the Candidate LBV 1806-20 & Nearby Cluster Stars | journal=The Astrophysical Journal | month=November | year=2004 | volume=Volume 616, Issue 1
pages=506–518 |url= http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2004ApJ...616..506E&amp;db_key=AST&amp;data_type=HTML&amp;format=&amp;high=44da334db710840 | doi=10.1086/422180]

There has been some dispute as to whether LBV 1806-20 is a single star or a cluster. Its luminosity has been estimated through very high-resolution speckle imaging, the results of which suggest that LBV 1806-20 may be a single star. However, more recent high-resolution spectroscopy reveals that there may be a companion and that the mass of each star in the system could be considerably less than 130 solar masses. [Cite journal | author=Figer, D.; Najarro, F.; Kudritzki, R. | title=The Double-lined Spectrum of LBV 1806-20 | journal=The Astrophysical Journal | month=August | year=2004 | volume=Volume 610, Issue 2 | pages=L109–L112 | url=http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2004ApJ...610L.109F&amp;db_key=AST&amp;data_type=HTML&amp; | doi=10.1086/423306]

Location

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).

References

ee also

* Cl* 1806-20 -- star cluster
* SGR 1806-20 -- soft gamma-ray repeater

External links

* [http://www.solstation.com/x-objects/1806-20.htm SolStation article]
* [http://arxiv.org/abs/astro-ph/0406316 The Double-Lined Spectrum of LBV 1806-20] , Donald F. Figer (STScI), Francisco Najarro (CSIC), Rolf P. Kudritzki (UH), 2004
* [http://arxiv.org/abs/astro-ph/0501560 Massive Stars in the SGR 1806-20 Cluster] , Donald F. Figer (STScI), Francisco Najarro (CSIC), T. R. Geballe (Gemini Observatory), R. D. Blum (CTIO), Rolf P. Kudritzki (UH), 2005