The pulsation sign

Cepheids: Pulsation, Evolution, Opacity

We describe modeling of the ''beat'' and "bump" Cepheids, using the new radiative opacities. Discrepancies between these models and the evolutionary tracks for stars of appropriate mass are discussed. Finally, we point out some of the difficulties involving the long-period Cepheid sample with periods greater than 20 days.

Analysis of the adiabatical pulsation of Cepheids

A model for the adiabatical pulsation of a Cepheid based on primary physical principles such as energy conservation, mechanical adiabaticity and hydrostatic equilibrium is presented. The adiabatical treatment of the pulsation has been already studied by other authors but the novelty of our model is that it allows to obtain physical parameters of the star, namely the amplitude of the oscillation...

Trauma or Tumor? The Nail Splay Sign

The State of Cepheid Pulsation Theory

We review the current state of Cepheid modeling and discuss its dominant deficiency, namely the use of time dependent mixing length. Notwithstanding, Cepheid modeling has achieved some excellent successes, and we mention some of the most recent ones. Discrepancies between observations and modeling appear not so much in the gross properties of single mode Cepheids, but rather when more subtle no...

The Pulsation Properties of Procyon A.

A grid of stellar evolution models for Procyon A has been calculated. These models include the best physics available to us (including the latest opacities and equation of state) and are based on the revised astrometric mass of Girard et al. Models were calculated with helium diffusion and with the combined effects of helium and heavy-element diffusion. Oscillation frequencies for l=0, 1, 2, an...