论文标题
星形行星相互作用和相关的射线射击的磁性水力学建模
Magnetohydrodynamic modelling of star-planet interaction and associated auroral radio emission
论文作者
论文摘要
我们介绍了使用磁层和电离层对流的全球磁流水动力学（MHD）建模计算的磁性热木星的极光射击射击恒太阳恒星的射线射击力的计算。传统上，使用经验或分析衍生的关系（例如辐射型兆律（RBL））估算了超级运动量的无线电功率，将无线电功率与恒星风格行李相互作用中消散的磁或动能相关联。这种方法有可能过分简化磁层电动力学，从而导致无线电发射。作为迈向自一致图片的下一步，我们使用3D MHD模型对恒星风层层层耦合电流进行建模。我们根据计算出的电离层场对准电流密度来计算电子-Cyclotron Maser不稳定性驱动的发射。我们表明，极光射电功率对星际磁场（IMF）强度高度敏感，并且对于合理的热木星Pedersen电导，发射饱和，这表明无线电功率可能在很大程度上独立于电离层电导。我们估计峰值无线电功率为$ 10^{14} $ W的$ w，暴露于IMF强度为$ 10^3 $ nt的行星，这意味着与当前和未来的射电望远镜可检测到的地球15 pc的通量密度在15 pc上。我们还发现无线电功率和行星轨道距离之间的关系，这与热木星在磁层 - 离子层偶联的先前分析模型的结果广泛一致，并表明RBL可能在热木星制度中最多高估了两种量的无线电功率。
We present calculations of auroral radio powers of magnetised hot Jupiters orbiting Sun-like stars, computed using global magnetohydrodynamic (MHD) modelling of the magnetospheric and ionospheric convection arising from the interaction between the magnetosphere and the stellar wind. Exoplanetary auroral radio powers are traditionally estimated using empirical or analytically-derived relations, such as the Radiometric Bode's Law (RBL), which relates radio power to the magnetic or kinetic energy dissipated in the stellar wind-planet interaction. Such methods risk an oversimplification of the magnetospheric electrodynamics giving rise to radio emission. As the next step toward a self-consistent picture, we model the stellar wind-magnetosphere-ionosphere coupling currents using a 3D MHD model. We compute electron-cyclotron maser instability-driven emission from the calculated ionospheric field-aligned current density. We show that the auroral radio power is highly sensitive to interplanetary magnetic field (IMF) strength, and that the emission is saturated for plausible hot Jupiter Pedersen conductances, indicating that radio power may be largely independent of ionospheric conductance. We estimate peak radio powers of $10^{14}$ W from a planet exposed to an IMF strength of $10^3$ nT, implying flux densities at a distance of 15 pc from Earth potentially detectable with current and future radio telescopes. We also find a relation between radio power and planetary orbital distance that is broadly consistent with results from previous analytic models of magnetosphere-ionosphere coupling at hot Jupiters, and indicates that the RBL likely overestimates the radio powers by up to two orders of magnitude in the hot Jupiter regime
