潮汐锁定下的热木星的形状及内部结构

Hot Jupiters represent a special class of extrasolar planets whose characteristics are alike to Jupiter in our solar system. Since the orbits of hot Jupiters are close to their host stars, the tidal effect plays an essential role in determining the physical and dynamical properties of hot Jupiters. An important feature is that they can reach, as a consequence of strongly tidal dissipation, spin-orbit synchronization in relatively short time. Under the strongly tidal and rotational influences, the shape of hot Jupiters usually becomes non-axisymmetric. The existing research has been limited to the equilibrium shape of rotationally and tidally distorted polytropes that depart only slightly from spherical geometry. Recently, Kong constructed a numerical model, based on a finite element method on modern massively parallel computers, that can be employed to calculate the axisymmetric shape and internal structure of Jupiter that departures substantially from spherical geometry. The proposed research is to extend, via a three-dimensional finite-element hybrid-inverse method, the Kong's axisymmetric model to a strongly non-axisymmetric model for hot Jupiters which are affected by both the rotational and tidal effects and that significantly depart from both spherical and axisymmetric geometry. Our proposed research will be able to provide the shape, internal structure and gravity field of hot Jupiters which cannot be directly measured by current observations. Moreover, the shape, internal structure and gravity field of tidally locked hot Jupiter obtained from our proposed research would offer a solid foundation based on that many important problems, such as atmospheric circulation, tidal dissipation and internal convection, can be further investigated.

热木星是一类和太阳系木星性质相似的系外行星，但是它们的轨道非常靠近母恒星，因此潮汐对此类天体起着控制作用。热木星轨道运动的潮汐耗散显著，可能在较短的时标内达到轨旋同步状态。在强烈自转和潮汐的共同作用下，热木星呈现明显的非轴对称形状。已有的研究采用近似理论讨论了受摄多方球的平衡形状，但仅适用于自转慢和潮汐弱的情况。最近孔大力构建了基于有限元和并行计算的数值模型，该模型局限于计算轴对称的太阳系木星的形状和内部结构。由于热木星形状、内部结构以及重力场无法直接观测，我们将拓展已有的轴对称模型，研究非轴对称的三维数值混合反演方法，通过有限的间接观测量自洽地给出热木星的形状、内部结构以及重力场信息，为研究潮汐锁定条件下热木星的大气环流、内部对流等问题提供不可或缺的基础。