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

大气湍流能量将自身分解为更小尺度的运动，直到它的能量完全转化为热、声和光。太阳和其他冷恒星外层的对流粒状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（色球层）的加热中起着关键作用。这一作用究竟有多重要仍然存在争议，因为人们发现，过去在评估太阳色球层的声热时所做的重要假设存在错误。首席研究员和他的合作者F. Cattaneo计划了一套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湍流的方程中计算出来。此外，他们的实验将包括包含磁通量管的等离子体湍流的影响，比如在太阳表面被认为是重要的。声能的计算将用于计算声波的加热，这可以直接与x射线观测到的太阳和其他恒星的发色团的冷却进行比较。预计这项工作将把恒星大气中声能的估计建立在一个坚实的实验基础上，并将允许估计恒星通过加热其外层大气而可能损失的最小质量。此外，它还可能导致地球上的大声源（例如喷气发动机）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).