Collaborative Project: On the Origin of Stellar Activity: Generation and Propagation of Wave Energy in the Surface Layers of Late-Type Dwarfs

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Atmospheric turbulent energy degrades itself into smaller scales of motion until its energy is converted entirely to heat, sound, and light. The convective granular motions of the outer envelope of the Sun and other cool stars are thought to convert their energy into acoustical energy, which is thought to play a key role in the heating of the outer atmosphere (chromosphere) of the Sun. Just how important this role may be is still controversial as an error has been found in important assumptions that have been made in the past to evaluate acoustical heating in the solar chromosphere. The Principal Investigator and his collaborator, F. Cattaneo, plan an extensive set of computer numerical simulations in which the excitation of acoustical energy will be computed from a set of equations describing turbulence in a three-dimensional compressional fluid. In addition, their experiments will include the effects of turbulence in plasma containing tubes of magnetic flux, such as are thought to be important on the Sun's surface. The computations of acoustic energy will be used to compute heating from sound waves which can be directly compared to the cooling of the chromopheres of the Sun and other stars from X-ray observations. It is anticipated that this work will put the estimates of acoustical energy in star's atmospheres on a firm, experimental basis and should permit estimates of the minimum amounts of mass that stars can lose through a heating of their outer atmospheres. In addition, it may lead to applications of the dissipation of energy from loud acoustical sources on the Earth (e.g. jet engines).