Luminous blue variable

Luminous blue variables (LBVs) are massive evolved stars.^[1] They show unpredictable and sometimes dramatic variations in their spectra and their brightness.

These unstable supergiants or hypergiants are also known as S Doradus variables. S Doradus is one of the brightest stars of the Large Magellanic Cloud.

LBVs are extraordinarily rare with just 20 listed in the General Catalogue of Variable Stars as SDor,^[2] and some of these are no longer considered to be LBVs.

In their "quiescent" state they are typically B-type stars, occasionally slightly hotter, with unusual emission lines. They are found in a region of the Hertzsprung–Russell diagram known as the S Doradus instability strip. They are the least luminous have a temperature around 10,000 K and a luminosity about 250,000 times the Sun. The most luminous have a temperature around 25,000 K and a luminosity over a million times the Sun. These are some of the most luminous of all stars.

Their relationship to supernovae is unclear.^[3]

1. ↑ 'Evolved' in this case means some millions of years old.
2. ↑ "GCVS Variability Types". General Catalogue of Variable Stars @ Sternberg Astronomical Institute, Moscow, Russia. 2009. Retrieved 2010-11-24.
3. ↑ Groh J.H; Meynet G. & Ekström S. 2013. Massive star evolution: luminous blue variables as unexpected supernova progenitors. Astronomy & Astrophysics 550: L7. [1]