Dissertation
Die Morphologie und Kinematik von Nebeln um Leuchkräftige Blaue Veränderliche
Kerstin Weis
Abstract:
During their evolution the most massive stars (> 50 MSun) enter an unstable phase
and with a strong mass loss (~ 10-3 MSun/yr). Stars in this phase
are called Luminous Blue Variables (LBVs). The strong mass loss leads to the formation of
nebulae around LBVs. In this thesis the analysis of several LBV nebulae reveals that bipolarity
in LBV nebulae seems to be a common feature rather then being present only in the nebula around
Eta Car. Kinematic and mophologic studies show that several other nebulae around LBVs show bipolar
components. The expansion velocity of the nebula around WRA 751 indicates that it is older.
I propose that LBV nebulae evolve along an evolutionary sequence, in which the nebula around
Eta Car represents the youngest member, the nebula around WRA 751 is an older, more evolved object.
Additional analyses of the outer nebula around Eta Car show that not only the inner Homunculus nebula
is bipolar, but also the outer filamentary part of the nebula, which consists of a large amount of
knots. A comparison of the X-ray emission of the nebula around Eta Car shows a quite different
morphology from the optical appearance. Using the kinematic information it was shown that the
X-ray emission originates from faster knots which produce shock fronts and emit in the X-ray band.
Finally, for the first time a LBV nebula with a major blowout was found, namly around the LMC star S119.
Thesis: ps.gz file (20133807 Bytes)
only available in German
