Magnetohydrodynamics in hot Jupiters

热木星的磁流体动力学

基本信息

批准号：
1775865
负责人：
金额：
--
依托单位：
Newcastle University
依托单位国家：
英国
项目类别：
Studentship
财政年份：
2016
资助国家：
英国
起止时间：
2016 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=studentship-1775865
关键词：
Magnetohydrodynamics hot Jupiters

项目摘要

The field of exoplanet research is relatively young with the first exoplanet orbiting a main-sequence star discovered in 1995. "Hot Jupiters" (Jupiter sized planets orbitingclose to their host stars) were the earliest discoveries and are the best characterized exoplanets due to their favorable observing conditions. They are also substantiallydifferent than the giant planets in our own solar system. For both of these reasons, hot Jupiters are an ideal test bed for theories of dynamical processes in gas spheres.Two of the most fundamental and long standing observational mysteries associated with these objects are: 1) How did hot Jupiters get to their current close positions(i.e. how did they form)? and 2) Why are they so big? In this project we will be focusing on the second of these two problems.Recent observations of hot Jupiters indicate that these objects are often substantially larger than standard evolutionary theory predicts. The inflated radii can only be explained by an injection of heat into the planetary interior, which halts gravitational contraction as the planet evolves. One of the leading theories is that Ohmicheating, due to the dissipation of electric currents, may cause this inflation. This project will use numerical simulations of the magnetohydrodynamic (MHD) equations in both cartesian and spherical geometry to quantify Ohmic dissipation under a variety of parameters typical of the observed hot Jupiters. More specifically, this project will investigate the effect of a fully temperature dependent magnetic diffusivity on the wind structure, magnetic field geometry and Ohmic dissipation within the atmosphere.The theories developed in this project will be incorporated into planetary evolution models and compared to observations of hot Jupiters. Such observations are already in abundance, but will multiply rapidly with current and future space missions dedicated. Additionally, our simulations will also inform on atmospheric dynamics, atmospheric loss rates and planetary spin down.

系外行星研究的领域相对较年轻，第一个外部外球星绕着1995年发现的主要序列恒星。“热木星”（木星大小的行星孔孔孔孔孔到他们的宿主恒星）是最早的发现，是最佳特征性的象征性的exoplanets，这是由于其良好的观察条件。它们也比我们自己的太阳系中的巨型行星大大不同。由于这两个原因，热木星都是气体球体动态过程理论的理想测试床。与这些物体相关的最基本和长期存在的观察性奥秘的两个是：1）热木星如何到达他们当前的近距离位置（即如何形成）？ 2）为什么它们这么大？在这个项目中，我们将重点放在这两个问题中的第二个问题上。热木星的观察结果表明，这些对象通常比标准进化理论预测的要大得多。膨胀的半径只能通过向行星内部注入热量来解释，随着行星的发展，它会停止重力收缩。领先的理论之一是，由于电流的耗散，俄亥俄州可能会导致这种通胀。该项目将使用笛卡尔和球形几何形状中磁性水动力（MHD）方程的数值模拟来量化观察到的热木星典型的多种参数下的欧姆耗散。更具体地说，该项目将研究完全依赖温度的磁扩散率对大气中的磁场几何形状和欧姆消散的影响。该项目中开发的理论将被纳入行星演化模型，并与热木星的观察结果相比。这样的观察已经很丰富，但是随着当前和未来的空间任务的迅速增长。此外，我们的模拟还将告知大气动态，大气损失率和行星旋转。