Effective temperatures of RCB stars.

Abstract

IUE observations and optical-IR photometry are reported for a number of R Coronae Borealis stars, including the LMC object W Men. Non-line-blanketed, hydrogen-deficient model atmospheres are normalized to the data in the IR to determine effective and color temperatures. By comparing stellar flux distributions with model atmosphere calculations, wavelength coverage can be used to estimate, for the first time, the extent to which the models (which do not include line blanketing) differ from the stellar flux distributions. The results are consistent with the supergiant status of these stars, and demonstrate that the absence of line blanketing in the models leads to overestimation of effective temperatures if models are fitted to long-wavelength data only.