Migration and Survival of Exoplanets near Magnetized Young Stars

康奈尔大学的一个研究小组进行的一项研究将模拟行星在主星磁场影响下的轨道迁移。观测提出了一个重要的问题：那些被认为形成于远离其主恒星的大型气态行星，通常被发现在离其主恒星非常近的地方运行。人们认为，气体行星在形成后，由于气体和尘埃盘内的摩擦而失去角动量，从而向宿主恒星迁移。然而，为什么这些行星没有落入恒星中还不清楚。当今行星科学的一个重要问题是了解它们是如何在离宿主恒星如此近的地方存活下来的。该小组将通过超级计算机模拟研究恒星磁场在行星生存和轨道分布中的作用。他们还将在当地的科学中心开发一个新的桌面天文学展览。该展览将教育公众关于磁铁的特性以及地球和太阳的磁场，并将为2024年在纽约州伊萨卡附近可见的日全食做好准备。一名研究生将积极参与行星轨道的建模，并在科学中心向公众解释科学。行星在旋转磁化恒星附近的迁移将在全局数值模拟中进行研究。这项调查将促进对年轻磁化恒星在系外行星迁移和生存中所起作用的理解。具体来说，他们将(1)研究行星在磁层空腔内的迁移和生存，考虑到它们与内盘的相互作用；(2)研究低质量行星在盘腔边界由于自转扭矩的迁移和俘获；(3)研究系外行星与内盘波的相互作用是否会改变其轨道的偏心率和倾角。该研究将使用三维磁流体力学代码：第一个是柱坐标代码，包含网格细化；第二个是立方球代码，过去广泛用于模拟磁化恒星的吸积。这两个代码都包含一个计算行星轨道的行星模块。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

A research investigation conducted by a team from Cornell University will simulate the orbital migration of planets under the influence of a host star's magnetic field. Observations present an important problem: large, gaseous planets that are thought to form far from their host stars are often found to orbit very close to their host stars. It is thought that after forming, gas planets migrate towards their host stars by losing angular momentum to friction within a disk of gas and dust. However, it is not understood why these planets do not fall into the star. An important problem in the science of planets today is understanding how they survive in such close proximity to their host stars. This team will investigate through supercomputer simulations what role the stellar magnetic field plays in the survival and orbital distribution of planets. They will also develop a new tabletop astronomy exhibit at the local Sciencenter. The Exhibit will educate the public about the properties of magnets and the magnetic fields of the Earth and Sun, and it will prepare them for the total Solar eclipse of 2024, which will be visible near Ithaca, NY. One graduate student will be actively involved in the modeling of planetary orbits and in explaining science to the public at the Sciencenter. Migration of planets in the vicinity of rotating magnetized stars will be studied in global numerical simulations. The investigation will advance understanding of the role that young magnetized stars play in the migration and survival of exoplanets. Specifically, they will (1) investigate the migration and survival of planets inside magnetospheric cavities, taking into account their interaction with the inner disk; (2) investigate migration and trapping of low-mass planets at disk-cavity boundaries due to corotation torque, and (3) study whether interactions of exoplanets with waves in their inner disks can change eccentricities and inclinations of their orbits. The investigation will use three-dimensional magneto-hydrodynamic codes: the first a code in cylindrical coordinates, which incorporates mesh refinement, and secondly the Cubed Sphere code, which has been used extensively in the past for modeling accretion onto magnetized stars. Both codes include a planetary module that calculates the orbits of planets.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.