Program: GS-2008A-Q-17

We request a small amount of time with Phoenix on Gemini South to obtain velocity profiles of the He I 10830 A line in the five known hydrogen-deficient carbon (HdC) stars and in one closely related Extreme Helium (EHe) star. We have recently discovered that both HdC stars and R Coronae Borealis (R CrB) stars have huge overabundances of 18O. This highly unusual property (not seen in any other stars) strongly implies that these two classes of stars have similar origins, and we and our colleagues are beginning to explore via modeling an earlier suggestion that they are created in the mergers of white dwarf binary pairs. Whether the two classes are formed in different types of (merger) events or represent an evolutionary sequence is unknown. R CrB stars are already known, via our earlier measurements of their He I 10830 line profiles, to have strong winds. There is only scant evidence for winds in HdC stars, but sensitive searches for winds in them have not been made. The proposed spectra will allow a direct comparison between the winds of the classes of objects and thus address the relationship between them.