Gone with the wind: Nebulae around LBVs
Astronomisches Institut, Ruhr-Universität Bochum, Bochum, Germany
Abstract
The LBV phase is a short and active phase very massive stars may pass. Strong stellar winds and possibly giant eruptions of the stars in this phase lead to the formation of small (≤ 5 pc) circumstellar nebulae. A significant fraction (about 50%) of these nebulae show—to different degrees—a bipolar structure. Such a morphology, together with the presence of LBVs at lower bolometric luminosity, supports the newer stellar evolution models including rotation. Morphology, kinematics and the chemical composition of LBV nebulae are useful tracers to reveal the star’s previous history, answer questions about the stellar interior and finally the stellar evolution of massive stars in general. A summary of our knowledge of the currently known LBV nebulae will be presented with a short special emphasis on a new analysis of the nebula around AG Carinae. Deep images and echelle spectra of this nebula show it to be much larger in size as known so far, and reveal in much more detail the—so far only hinted—highly bipolar structure of the nebula.