Tides and Atmospheres for Hot Jupiters

AST 0707373 Goodman此时，至少有40颗太阳系外行星围绕主序星运行，它们的公转周期小于10天，最小质量小于10个木星质量。这些“热彗星”的发现违背了以前基于太阳系的经验。它们详细的轨道和物理性质呈现出几个特定的谜团，这可能是它们的起源，内部结构和早期原恒星环境的线索。为什么它们的平均质量明显小于周期较长的行星？为什么月经高峰在3天左右？ 为什么它们的轨道不那么偏心？假设它们在更大的轨道上形成并向内迁移，为什么热彗星没有一直迁移到它们的恒星中，或者我们只看到了一个更大的初始种群的幸运幸存者？“热海王星”曾经是遭受严重质量损失的热海王星吗？在为数不多的热彗星中，由于经过恒星而具有确定的半径，为什么这些半径中的许多比直接模型预测的要大或小？ 很可能许多解都涉及行星和它的星星之间的潮汐或辐射相互作用，因为这些影响强烈地依赖于轨道距离。基于过去在天体物理流体动力学中潮汐和其他问题的经验，杰里米·古德曼博士的研究小组将研究潮汐耗散、辐射和质量损失之间的相互关系，特别关注热对流层的外层。这些工具将是半分析估计和一维计算，而不是多维模拟。潮汐耗散是理论天文学中最古老的未解决的问题之一。由于它们的低表面重力和无法燃烧氢，热彗星在结构上比恒星对潮汐消散更敏感，可能更好地保存了过去潮汐影响的“记忆”。因此，对这些天体的研究可能会产生适用于更普遍的潮汐相互作用的见解。除此之外，太阳系外的行星也引起了公众和专业天文学家的极大兴趣，因为它们可能会告诉我们太阳系的历史，甚至可能是地球以外生命的可能性。***

AST 0707373GoodmanAt this time, there are at least forty extrasolar planets orbiting main-sequence stars with well-determined periods of less than 10 days and minimum masses less than 10 Jupiter masses. The discovery of these "hot Jupiters" defied previous experience based on the Solar System. Their detailed orbital and physical properties present several specific mysteries, which are probablyclues to their origins, internal structure, and early protostellar environment. Why are their masses significantly smaller on average than those of planets with longer periods? Why do the periods peak at ~3 days? Why are their orbits less eccentric? Presuming that they formed on larger orbits and migrated inward, why did the hot Jupiters not migrate all the way into their stars, or do we see only the lucky survivors of a much larger initial population? Were "hot Neptunes" once hot Jupiters that suffered severe mass loss? Among the few hot Jupiters that have well-determined radii by virtue of transiting their stars, why are many of these radii significantly larger or smaller than straightforwardmodels predict? It is likely that many of the solutions involve tidal or radiative interactionsbetween the planet and its star, as these influences depend strongly on orbital distance. Building upon past experience with tides and other problems in astrophysical fluid dynamics, Dr. Jeremy Goodman's research team will investigate the interrelations between tidal dissipation, irradiation, and mass loss, with particular attention to the outer layers of hot Jupiters. The tools will be semianalytic estimates and one dimensional calculations rather than multidimensional simulations. Tidal dissipation is among the oldest unsolved problems in theoretical astronomy. Because of their low surface gravity and inability to burn hydrogen, hot Jupiters are structurally more sensitive to tidal dissipation than stars and may better preserve a "memory" of past tidal influences. So thestudy of these objects may yield insights applicable to tidal interactions more generally. Besides, extrasolar planets are of great interest to the public as well as to professional astronomers because of the lessons they may have to teach about the history of our own solar system, and perhaps even the possibilities for life beyond earth. ***