A nonlinear analysis of the radial pulsations in R Coronae Borealis stars.
Abstract
The properties of radial pulsations in models of R Coronae Borealis (R CrB) stars have been investigated by using a nonlinear hydrodynamic code. The pulsation amplitude grows without attaining a limit (so far as computed) in the lowmass (M less than 1.6 solar mass) models if T(e) = 6300 K is adopted, while the amplitude is bounded even in models with M of less than 1 solar mass if T(e) of about 7000 K is adopted. The latter value of the effective temperature is consistent with the results of spectroscopic studies of pulsating R CrB stars. In the models with T(e) of about 7000 K, a strong shock wave appears around the phase of the minimum light, while the shock wave is weak in the models with T(e) of about 6000 K. Because of the strong shock wave, light and velocity curves and the period of pulsation are irregular in the lowmass models with T(e) of about 7000 K. The periods of nonlinear pulsation in such largeamplitude pulsations are longer than those obtained from linear analysis by up to about 20 percent.
 Publication:

The Astrophysical Journal
 Pub Date:
 August 1985
 DOI:
 10.1086/163346
 Bibcode:
 1985ApJ...295...38S
 Keywords:

 B Stars;
 R Coronae Borealis Stars;
 Stellar Models;
 Stellar Oscillations;
 Supergiant Stars;
 Variable Stars;
 Hydrodynamics;
 Nonlinearity;
 Pulse Amplitude;
 Shock Waves;
 Stellar Temperature;
 Astrophysics