Recent work on Cepheid variables

Recent work on Cepheids is reviewed in the areas of (1) the large-amplitude mode behavior, (2) convection, and (3) Cepheid masses. Initial-value type nonlinear calculations have not yet yielded true double-mode behavior, but the beginnings of a theory of modal selection are formulated. Recent observational results have led to increased values of the 'pulsation mass', so that this mass is now in agreement with the evolution theory; the 'Wesselink mass' is also satisfactory. The proposal of helium enrichment in the outer stellar layers should satisfactorily resolve the beat (and perhaps also the bump) mass anomaly. A suggestion that part of the pressure in the envelope is due to a tangled magnetic field resolves the mass anomaly about as well as the helium-enrichment hypothesis.