The zone of avoidance in the Hertzsprung-Russell diagram.
M sol or with low metallicities.
The cause of instability is the partial ionization of hydrogen and helium in a quasi-isolated outer region of the stellar envelope, above the layer where the iron opacity attains a large local maximum. Predicted luminosities, effective temperatures, ejected nebular masses, remnant masses, eruption recurrence times, and lifetimes, though very approximate, are generally cinsostent with available observational data for the important class of unstable supergiants known as luminous blue variables. Return to the publications menu .