Effects of Dust on the Propagation of Shock Waves in Circumstellar Envelopes of Late-Type Variable Stars

Abstract

Physical processes affecting propagation of moderate-strength shocks in the inner parts of circumstellar envelopes of Miras are considered. In particular, the influence of dust, which is heated later than heavy gas particles, is critical for pumping of circumstellar H₂O masers. Strong shocks with Mach numbers M exceeding ∼ 10 destroy dust and molecules and partly ionize the gas. Weaker shocks with 3 < M < 10 spend their energy mainly to dissociate molecules. Shocks with 1 < M < 3 lose their energy via heating of dust and may stimulate formation of dust. Some implications are discussed.