论文标题
系外行星无线电作为探针的探针 - 时间依赖性的MHD模拟
Exoplanet Radio Transits as a Probe for Exoplanetary Magnetic Fields -- Time-dependent MHD Simulations
论文作者
论文摘要
我们对HD 189733 Star-Planet系统进行一系列依赖性的磁流失动力学模拟，以预测由于恒星风与行星磁场之间的相互作用而导致的无线电运输调制。该模拟将恒星电晕和风的模型与外界的模型结合在一起，该模型以完全动态的，时间依赖的方式绕着恒星绕行。我们的模拟生成合成无线电图像，使我们能够以不同频率获得合成无线电曲线。我们在无线电曲线中找到了行星运动的明确证据。此外，我们在光曲线中发现了特定的重复特征，这些特征归因于恒星在运输过程中恒星前面的行星磁层的通过。更重要的是，我们发现这些灯曲线特征对行星磁场强度的大小和相位有明显的依赖性。我们的工作表明，如果可以观察到无线电传输，它们确实可以提供有关过渡系外行星的磁场强度的信息。未来的工作来参数化这些Lightcurve功能及其对行星场强度的依赖将提供在无线电观测数据集中搜索这些功能的工具。由于我们仅考虑宿主恒星的热无线电发射以进行研究，因此必须非常敏感的无线电干涉仪来检测无线电中的这类行星传输。
We perform a series of time dependent Magnetohydrodynamic simulations of the HD 189733 star-planet system in order to predict radio transit modulations due to the interaction between the stellar wind and planetary magnetic field. The simulation combines a model for the stellar corona and wind with an exoplanet that is orbiting the star in a fully dynamic, time-dependent manner. Our simulations generate synthetic radio images that enable us to obtain synthetic radio lightcurves in different frequencies. We find a clear evidence for the planetary motion in the radio light curves. Moreover, we find specific repeated features in the light curves that are attributed to the passage of the planetary magnetosphere in front of the star during transit. More importantly, we find a clear dependence in the magnitude and phase of these lightcurve features on the strength of the planetary magnetic field. Our work demonstrates that if radio transits could be observed, they could indeed provide information about the magnetic field strength of the transiting exoplanet. Future work to parameterize these lightcurve features and their dependence on the planetary field strength would provide tools to search for these features in radio observations datasets. As we only consider the thermal radio emission from the host star for our study, very sensitive radio interferometers are necessary to detect these kinds of planetary transit in radio.
