What's New With R Coronae Borealis Stars? (Abstract)

Volume 31 number 2 (2003)

Geoffrey Clayton

Abstract

(Abstract only) I present new observational data concerning the R Coronae Borealis (RCB) stars and their evolutionary status. There are two major models for the origin of RCB stars: the Double Degenerate and the Final Helium Shell Flash. In the final flash model, there is a close relationship between RCB stars and Planetary Nebulae (PNe). The connection between RCB stars and PNe has recently become stronger, since the central stars of three old PNe (Sakurai’s Object, V605 Aql, and FG Sge) have had observed outbursts that transformed them from hot evolved central stars into cool giants with the spectral properties of an RCB star. I also discuss new RCB stars recently identified in the Galaxy and in the Large Magellanic Cloud (LMC) using the MACHO project photometry database. The absolute luminosities of the Galactic RCB stars are unknown since there is no direct measurement of the distance to any Galactic RCB star, hence, the importance of the LMC RCB stars.