Hubble-Sandage variables

Hubble–Sandage variables

The most massive and luminous stars (M v < –9 and all spectral types) occurring in the nearby galaxies M31 and M33. Like other highly massive stars, they are variable stars. The variations in brightness, discovered by E. Hubble and A. Sandage in 1953, were in most cases slow, small, and irregular although some displayed much greater variation. They are members of the class of luminous blue variables.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006