NEBULAE AROUND LUMINOUS BLUE VARIABLES - A UNIFIED PICTURE

The study of the nebulae around luminous blue variables (LBVs) provides clues to the mass-loss history of massive stars before and during the LBV phase. In this paper we investigate the possibility that the LBV nebulae (LBVNs) are shaped by interacting winds. We compare the morphologies of all known nebulae around LBVs, by compiling the results of our detailed coronagraphic imaging and spectroscopic studies of individual LBVs and their nebulae together with other relevant information from the literature. Most LBVs exhibit axisymmetric morphologies, suggesting that a single basic formation mechanism is involved. We propose that a model which consists of a stellar wind interacting with a preexisting density contrast (between the equatorial and polar directions) can explain most observed morphologies. There are several mechanisms which can produce the necessary density contrast, and at present it is difficult to determine definitively whether one or more of these mechanisms have been operating in the different systems.