Static and Dynamical Models of Long-Period Variable Stars

Citation

Keeley, Douglas Allan (1970) Static and Dynamical Models of Long-Period Variable Stars. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/NTN2-HH47. https://resolver.caltech.edu/CaltechETD:etd-05072008-142808

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. The parameters of the models were M=1 and 1.3M[...], M[subscript B] = -3.8 to -5, and T[subscript e] = 2200[...]K. The equation of state included a detailed calculation of ionization equilibrium and the dissociation of H2, OH, CO, and H2O. The opacity of CO, OH, and H2O was included. The dynamical calculations show that large-amplitude pulsation can occur in convective models. The opacity mechanism causes strong driving of the pulsation in the region outside the hydrogen ionization zone, and the [gamma]-mechanism results in very low dissipation in the hydrogen zone. The phase relation between the bolo-metric luminosity and the radius variations is similar to that of Cepheids. The static models have large ionization and dissociation zones, which cause the pulsation parameter Q=P[subscript days](p/p[...])[...] to become greater than 0.15 in some models. The fundamental periods range from 180 days to greater than 2000 days; the overtone periods are about [...] as long. The positions of many observed stars in the theoretical HR diagram suggest that their periods should be associated with the overtone periods of the models.

Thesis Files