Galactic twins of the nebula around SN 1987A: Hints that LBVs may be supernova progenitors

I discuss outstanding questions about the formation of the ring nebula around SN1987A and some implications of similar ring nebulae around Galactic B supergiants. There are notable obstacles for the formation of SN1987A's bipolar nebula through interacting winds in a transition from a red supergiant to a blue supergiant. Instead, several clues hint that the nebula may have been ejected in an LBV-like event. In addition to the previously known example of Sher 25, there are two newly-discovered Galactic analogs of SN1987A's ringed nebula. Of these three Galactic analogs around blue supergiants, two (Sher 25 and SBW1) have chemical abundances indicating that they have not been through a red supergiant phase, and the remaining ringed bipolar nebula surrounds a luminous blue variable (HD168625). Although SK - 69 202's initial mass of ∼20M _⊙ is lower than those atributed to most LBVs, it is not far off and the low-luminosity end of the LBV phenomenon is not well defined. Furthermore, HD168625's luminosity indicates an initial mass of only ∼25M _⊙, that of SBW1 is consistent with ∼20M _⊙, and there is a B[e] star in the SMC with an initial mass of ∼20M _⊙ that experienced an LBV outburst in the 1990s. These similarities may be giving us important clues about Sk - 69 202's pre-SN evolution and the formation mechanism of its nebula.