Pulsations of the R Coronae Borealis Stars

The radial pulsations of very luminous, low-mass models (L/M ˜ 10 4 , solar units), which are possible representatives of the R CrB stars, have been examined. These pulsations are extremely nonadia – batic. We find that there are in some cases at least one extra (“strange”) mode which makes interpretation difficult. The blue instability edges are also peculiar, in that there is an abrupt excursion of the blue edge to the blue for L/M sufficiently large. The range of periods of the model encompasses observed periods of the Cepheid-like pulsations of actual R CrB stars.