There are several physical processes that mediate the interaction between an exoplanet and its host star, with the four main ones being due to magnetic, particle (stellar outflow), radiative, and tidal interactions. These interactions can be observed at different wavelengths, from X-ray to radio. Their strengths depend on the architecture of planetary systems, as well as the age and activity level of the host stars. In particular, exoplanets in close-in orbits and/or orbiting active host stars can experience strong physical interactions, some of which are negligible or absent in the present-day Solar System planets. Here, I present an overview of star–planet interactions (SPIs) through the lens of three-dimensional (3D) numerical models. The main conclusions are as follows: ▪ Models are fundamental to interpret and guide observations. The powerful combination of observations and models allows us to extract important physical parameters of the system, such as planetary magnetic fields, stellar wind properties, etc. ▪ The nonaxisymmetric forces of the interactions generate spatially asymmetric features (e.g., planetary material trailing the orbit, shock formation), thus requiring the use of 3D models. ▪ SPIs vary in different timescales (from hours to gigayears) that are related to both planetary (orbital motion, rotation) and stellar (flares, cycles, and long-term evolution) properties. Understanding these variations requires time-dependent models. I advocate that future 3D models should be informed by multiwavelength, (near-)simultaneous observations. The use of observations is twofold: some generate inputs for models (e.g., stellar magnetic field maps), whereas others are fitted by models (e.g., spectroscopic transits). This combination of observations and models provides a powerful tool to derive physical properties of the system that would otherwise remain unknown.

中文翻译：

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星-行星相互作用：计算视图

有几种物理过程可以介导系外行星与其宿主恒星之间的相互作用，其中四个主要过程是由于磁、粒子（恒星流出）、辐射和潮汐相互作用。这些相互作用可以在不同的波长下观察到，从 X 射线到无线电。它们的优势取决于行星系统的架构，以及宿主恒星的年龄和活动水平。特别是，位于近距离轨道和/或围绕活跃宿主恒星运行的系外行星可能会经历强烈的物理相互作用，其中一些在当今太阳系行星中可以忽略不计或不存在。在这里，我通过三维 （3D） 数值模型的镜头概述了星-行星相互作用 （SPI）。主要结论如下：▪模型是解释和指导观察的基础。观测和模型的强大组合使我们能够提取系统的重要物理参数，例如行星磁场、恒星风特性等。▪相互作用的非轴对称力会产生空间不对称特征（例如，行星物质拖曳轨道、激波形成），因此需要使用 3D 模型。▪ SPI 在不同的时间尺度（从数小时到千兆年）中有所不同，这与行星（轨道运动、旋转）和恒星（耀斑、周期和长期演化）特性有关。了解这些变化需要瞬态模型。 我主张未来的 3D 模型应该由多波长、（近）同步观测来提供信息。观测的用途是双重的：一些为模型生成输入（例如，恒星磁场图），而另一些则由模型拟合（例如，光谱凌日）。 这种观测和模型的结合提供了一个强大的工具，可以推导出系统的物理特性，否则这些物理特性将保持未知。