R coronae borealis stars and their relation to [WC] nebulae

Geoffrey C. Clayton, Louisiana State University


The R Coronae Borealis (RCB) stars represent a rare, or short-lived stage of low and intermediate mass stellar evolution. They are important in the context of mass-loss and dust formation on the Asymptotic Giant Branch. These stars are defined by their large declines in brightness at irregular intervals caused by dust formation. There are two major evolutionary models for the origin of RCB stars, the Double Degenerate and the Final Helium Shell Flash. In the final flash model, RCB stars lie at the centers of old Planetary Nebulae (PN). Here I discuss possible relationships with the [WC] stars.