Astronomy Colloquium

I will discuss the role that mass loss plays in the pre-supernova evolution of massive stars in a variety of different scenarios, and what observable effect it may have on the resulting SN explosion. The amount of mass lost, its speed, and how soon before core collapse the material is lost can have a dramatic effect on the resulting SN lightcurve and spectrum. Massive stars trek across the HR diagram as they evolve, and
the resulting SN can look very different depending on where along this path core collapse occurs. It may not depend solely on initial mass, because many of the potential progenitors of Types Ib, Ic, IIn, IIb, and II-L overlap in their range of likely initial mass. It will therefore be very difficult to use SNe as probles of stellar evolution until this connection is understood. The most extreme pre-SN mass ejections in massive luminous blue variables (LBVs) have recently (and surprisingly) been linked to the very luminous Type IIn supernovae with extremely strong circumstellar interaction that dominates the spectrum and enhances the visual luminosity. In some cases these objects require strong LBV-like shell ejections in the decades immediatley before a SN. This may suggest
that some massive stars become surprisingly unstable in the very final stages of nuclear burning before core collapse, for reasons that are not yet fully understood.