Gravity mode in gas-dust envelope of an oscillating star

Abstract

The hydrodynamic mechanism of gravitational coupling between seismic vibrations of a star and fluctuations of gas-dust flows in stellar envelope is discussed. Working from a homogeneous model of a spherical stellar cocoon-a star embedded in a thick dusty shell, the self-consistent equations of hydro-gravity, formulated as a counterpart of equations of hydro-magnetic model of interstellar,gas-dynamics, are introduced. Particular attention is given to shear oscillations of ambient gas-dust matter triggered by seismic pulsations of a star owing its existence to circumstellar gravitational stresses. It is shown that, in the absence of accretion. the frequency of this gravity-driven mode in circumstellar envelope is proportional to the frequency of the g-mode in the star bulk. The implication of the model to a number of current astrophysical problems is briefly discussed.