热木星中由磁流体热电阻不稳定性引起的热斑偏移变率
Hot Spot Offset Variability from Magnetohydrodynamical Thermoresistive Instability in Hot Jupiters
AI总结：
本研究拓展了热木星大气的轴对称一维径向模型，通过经度方向一阶傅里叶展开表示温度与磁扩散率，预测热电阻不稳定性发展及阿尔文振荡期间的热斑偏移，发现峰值通量偏移数天内可在±60°间变化，为热木星的可观测特征提供了新解释。
摘要：
热木星大气可能会受到热电阻不稳定性的影响。当欧姆加热以正反馈循环提升电导率时，这类不稳定性可能会发展，最终导致大气温度失控。我们对之前的轴对称一维径向模型进行了拓展，将温度和磁扩散率表示为经度方向的一阶傅里叶展开。这使得我们能够预测热电阻不稳定性发展过程中以及随后的阿尔文振荡期间的热斑偏移。我们展示了一个发生热电阻不稳定性的代表性模拟，其中峰值通量偏移在数天的时间尺度上在约±60°之间变化，可能伴随可观测的亮度变化。因此，只要观测和凌日的时机合适且行星参数匹配，这种热电阻不稳定性可能成为热木星的一个可观测特征。
英文摘要：
Hot Jupiter atmospheres are possibly subject to a thermoresistive instability. Such an instability may develop as the ohmic heating increases the electrical conductivity in a positive feedback loop, which ultimately leads to a runaway of the atmospheric temperature. We extend our previous axisymmetric one-dimensional radial model, by representing the temperature and magnetic diffusivity as a first order Fourier expansion in longitude. This allows us to predict the hot spot offset during the unfolding of the thermoresistive instability and following Alfvénic oscillations. We show a representative simulation undergoing the thermoresistive instability, in which the peak flux offset varies between approximately $\pm 60^{\circ}$ on timescales of a few days with potentially observable brightness variations. Therefore, this thermoresistive instability could be an observable feature of hot Jupiters, given the right timing of observation and transit and the right planetary parameters.
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