Impact of pulsation on the structure of circumstellar envelopes

Correlations between the stellar parameters and circumstellar parameters of long-period variables are discussed, and a strong influence of the period on the structure of the circumstellar envelope is established. Observational results along with nonregular period variations detected during monitoring observations are used for exploring a model based on a perturbed Keplerian oscillator, in which the star is composed of two oscillators: the interior acting as the driving oscillator and the mantle representing the driven oscillator. It is demonstrated that period variations and long-term amplitude are the generic features of the driven oscillator, and that the initial conditions are critical for the behavior of the mantle. 7 refs