C/He abundances in WC stars

The C/He abundances in 17 southern WC stars have been derived from spectra in the H and K bands using, for the most part, recombination theory with allowance for collision redistribution. As appropriate calculations for CIII are not available, two extremes are considered; LTE treatment of CIII gives C/He values that range from 0.04 to 0.3, by number. Maximum allowance for possible non-LTE effects gives values from 0.1 to 0.7, by number. C/He decreases from WC4 to WC7. C/He in WC8 and 9 stars is uncertain because of contributions from C2+ and possibly neutral helium, but may be as high as for WC5-7 stars. (author)