Intermittent Transition to Irregular Pulsation with Mass Loss in Hydrodynamic Models

Abstract

Hydrodynamic simulations of non-linear pulsation for less-massive cooler supergiants have been perfoemed by several authors (Tuchman, Sack and Barkat, 1979; Fadeyev and Tutukov, 1981; Fadeyev, 1982, 1984; Nakata, 1987; Buchler et al., 1987). The outburst of large amplitude pulsation at times is one of common features of these models, and renders mass-loss from the atmosphere of pulsating stars by generating strong shock waves.To find out routes of the transition from limit cycles to this type of irregular pulsation, we performed hydrodynamic simulations for a series of models the luminosity log(L/L⊙ ) = 3.505, and Te = 5300 K with a narrow range of the mass, 1.4 M⊙<M<1.5 M⊙ by using the hydrodynamic code, TGRID (Simon and Aikawa, 1986).