Tidal dissipation in stars and planets: simulations from first principles

许多太阳系外行星围绕恒星运行的时间只有几个地球日。在如此近的距离，重力潮汐相互作用可以在改变行星轨道以及恒星和行星自转方面发挥重要作用。这些进化过程的时间尺度取决于潮汐流动能在恒星和行星内部的消散效率，但从理论上讲，这一点还没有得到很好的理解。这个项目本质上是计算性的，将涉及第一原理数值模拟，在高性能计算机上使用最先进的算法，以探索恒星和行星流体层中的潮汐消散机制。特别是，我建议研究旋转恒星中潮汐流动和湍流对流流动之间的相互作用，以及导致恒星(和行星)自转和行星轨道对齐的机制。这些模拟的结果将被用来解释天体物理观测，并做出预测，例如，拥有行星的恒星的自转速度，以及在其恒星前面运行的最短周期行星可能的轨道衰变。这些预测可以通过使用例如SuperWASP、NGTS、Cheops、Tess和柏拉图的未来观察来验证。

Many extrasolar planets orbit their stars in only a few Earth days. At such close distances, gravitational tidal interactions can play an important role in modifying planetary orbits and stellar and planetary spins. The timescales for these evolutionary processes depend on how efficiently the kinetic energy of tidal flows is dissipated inside stars and planets, but this is not well understood theoretically. This project is computational in nature and will involve first principles numerical simulations, employing state-of-the-art algorithms on high-performance computers, to explore the mechanisms of tidal dissipation in the fluid layers of stars and planets. In particular, I propose to investigate the interaction between tidal flows and turbulent convective flows in rotating stars, and the mechanisms that lead to alignment of the stellar (and planetary) spin and the planetary orbit. The results from these simulations will be used to interpret astrophysical observations and to make predictions, for example, of the rotation rates of planet-hosting stars, and of possible orbital decay of the shortest-period planets that transit in front of their stars. These predictions can be tested by future observations using e.g. SuperWASP, NGTS, CHEOPS, TESS and PLATO.