Simulating the environment around planet-hosting stars II. Stellar winds and inner astrospheres
Simulating the environment around planet-hosting stars II. Stellar winds and inner astrospheres
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DOI：
10.1051/0004-6361/201628988
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发表时间：
2016-10-01
影响因子：
6.5
通讯作者：
Gombosi, T. I.
中科院分区：
文献类型：
--
作者：
Alvarado-Gomez, J. D.;Hussain, G. A. J.;Gombosi, T. I.
我们给出了三颗系外行星-宿主恒星(HD1237、HD22049和HD147513)周围环境的综合数值模拟结果。我们的模拟考虑了目前用于日光层空间天气研究的最新模型之一，将湍流Alfven波耗散作为日冕加热和恒星风加速的来源。用塞曼-多普勒成像层析成像技术的两种实现方式恢复的大规模磁场图，用于在每个系统中驱动稳态解决方案。这篇文章描述了恒星风和内部天体，而日冕结构在以前的文章中已经讨论过了。分析包括恒星风的磁流体力学性质，相关的质量和角动量损失率，以及每个系统中天体电流片的拓扑结构。对所考虑的情况进行了系统的比较，包括包括最小和最大活动的两个参考太阳模拟。对于HD1237，我们研究了发展的恒星风的结构与该系统中木星质量行星周围可能存在的磁层之间的相互作用。我们发现，粒子注入行星大气的过程是由密度分布决定的，而不是由恒星风的速度分布决定的。在这一背景下，我们预测在该系统中40 MHz的最大行星外射电辐射为12mJy，假设在近地星体通过期间穿过一个高密度流光。此外，结合本研究第一篇论文中的分析，我们首次得到了一个完全模拟的质量损失-活性关系。这一关系在之前提出的观测对应物的背景下进行了比较和讨论，该观测对应物是由天球探测得出的。最后，我们提供了这些系统的恒星风的全球3D特性的特征，在它们的宜居地带的内缘。
We present the results of a comprehensive numerical simulation of the environment around three exoplanet-host stars (HD 1237, HD22049, and HD147513). Our simulations consider one of the latest models currently used for space weather studies in the Heliosphere, with turbulent Alfven wave dissipation as the source of coronal heating and stellar wind acceleration. Large-scale magnetic field maps, recovered with two implementations of the tomographic technique of Zeeman-Doppler imaging, serve to drive steady-state solutions in each system. This paper contains the description of the stellar wind and inner astrosphere, while the coronal structure was discussed in a previous paper. The analysis includes the magneto-hydrodynamical properties of the stellar wind, the associated mass and angular momentum loss rates, as well as the topology of the astrospheric current sheet in each system. A systematic comparison among the considered cases is performed, including two reference solar simulations covering activity minimum and maximum. For HD1237, we investigate the interactions between the structure of the developed stellar wind, and a possible magnetosphere around the Jupiter-mass planet in this system. We find that the process of particle injection into the planetary atmosphere is dominated by the density distribution rather than the velocity profile of the stellar wind. In this context, we predict a maximum exoplanetary radio emission of 12 mJy at 40 MHz in this system, assuming the crossing of a high-density streamer during periastron passage. Furthermore, in combination with the analysis performed in the first paper of this study, we obtain for the first time a fully simulated mass loss-activity relation. This relation is compared and discussed in the context of the previously proposed observational counterpart, derived from astrospheric detections. Finally, we provide a characterisation of the global 3D properties of the stellar wind of these systems, at the inner edges of their habitable zones.