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Galactic distribution and absolute magnitudes

The distribution of galactic RCB stars is controversial. Several authors have argued that they belong to a thick galactic disk, and are thus old Population I stars. However, they may alternatively belong to the even older galactic bulge (Population II). The controversy may simply be a result of the different ways in which surveys for RCB stars and related objects have been carried out. In either case, the populations are sufficiently old that RCB stars must have relatively low masses ( $\leq{\rm 1 M_{\odot}}$).

A growing number of RCBs have been discovered in the Large MAGELLANIC CLOUD (LMC), most recently as a result of wide field surveys. These are the only RCB stars for which a distance is known and hence for which an absolute magnitude can be deduced. With $M_{\rm V}\sim-4$ to -5, the LMC RCBs are 3000 - 10000 times more luminous than the Sun.

Simon Jeffery