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

大气湍流能量会退化成更小的运动尺度，直到它的能量完全转化为热、声和光。太阳和其他冷星外壳的对流颗粒运动被认为将它们的能量转化为声能，这被认为在太阳外层大气(色层)的加热中起着关键作用。这种作用到底有多重要仍存在争议，因为在过去评估太阳色球声学加热的重要假设中发现了错误。首席研究员和他的合作者F·卡特内奥计划进行一系列广泛的计算机数值模拟，其中声能的激发将从一组描述三维压缩流体中的湍流的方程中计算出来。此外，他们的实验将包括含有磁通量管的等离子体中的湍流效应，例如被认为对太阳表面很重要的磁通量管。声波能量的计算将被用来计算声波的加热，这可以直接与太阳和其他恒星从X射线观测到的生色团的冷却进行比较。预计这项工作将使对恒星大气中声能的估计建立在坚实的实验基础上，并应该能够估计恒星通过加热外层大气而损失的最小质量。此外，它可能导致地球上巨大声源(例如喷气式发动机)的能量耗散的应用。

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).