Tides and Atmospheres for Hot Jupiters

AST0707373古德曼此时，至少有40颗太阳系外行星围绕主序恒星运行，它们的周期确定不到10天，最小质量小于10木星质量。这些“热木星”的发现打破了之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具体的谜团，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比周期较长的行星要小得多？为什么周期在~3天达到峰值？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，为什么热木星没有一直迁移到它们的恒星中，或者我们只看到了更大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木星吗？在少数几个通过凌日而具有明确半径的热木星中，为什么许多这样的半径比直接的模型预测的要大得多或小得多？许多解决方案很可能涉及行星和恒星之间的潮汐或辐射相互作用，因为这些影响强烈依赖于轨道距离。基于过去天体物理流体动力学中潮汐和其他问题的经验，Jeremy Goodman博士的研究团队将研究潮汐耗散、辐射和质量损失之间的相互关系，并特别关注热木星的外层。这些工具将是半解析估计和一维计算，而不是多维模拟。潮汐耗散是理论天文学中最古老的悬而未决的问题之一。由于表面重力低，不能燃烧氢，热木星在结构上比恒星对潮汐消散更敏感，可能更好地保存对过去潮汐影响的“记忆”。因此，对这些天体的研究可能会产生更普遍适用于潮汐相互作用的见解。此外，太阳系外的行星引起了公众和专业天文学家的极大兴趣，因为它们可能需要教授我们自己太阳系的历史，甚至可能是地球以外的生命的可能性。***

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. ***