论文标题
量化产生II型无线电爆发的冠状冲击的磁性结构
Quantifying the Magnetic Structure of a Coronal Shock Producing a Type II Radio Burst
论文作者
论文摘要
II型无线电爆发被认为是由太阳大气中的冲击波产生的。但是，II型无线电爆发需要什么磁性条件仍然是一个令人困惑的问题。在这里，我们量化了与II型无线电爆发相关的冠状冲击的磁性结构。基于多观测性极端脉冲观测，我们重建了三维（3D）冲击表面。通过使用磁场外推模型，我们将磁场相对于冲击阵线的正常（$θ_{\ rm bn} $）和alfvén马赫数（$ m_a $）得出磁场的方向。结合了Nancay Radio Heliograph中的无线电观察结果，我们获得了冲击阵线上II型无线电爆发的源区域。发现无线电突发是由$ M_A \ gtrsim 1.5 $和$θ_{bn} $的双峰分布产生的。我们还使用Rankine-Hugoniot关系来量化下游冲击的性质。我们的结果提供了产生II型无线电爆发的冠状冲击的定量3D磁性结构条件。
Type II radio bursts are thought to be produced by shock waves in the solar atmosphere. However, what magnetic conditions are needed for the generation of type II radio bursts is still a puzzling issue. Here, we quantify the magnetic structure of a coronal shock associated with a type II radio burst. Based on the multi-perspective extreme-ultraviolet observations, we reconstruct the three-dimensional (3D) shock surface. By using a magnetic field extrapolation model, we then derive the orientation of the magnetic field relative to the normal of the shock front ($θ_{\rm Bn}$) and Alfvén Mach number ($M_A$) on the shock front. Combining the radio observations from Nancay Radio Heliograph, we obtain the source region of the type II radio burst on the shock front. It is found that the radio burst is generated by a shock with $M_A \gtrsim 1.5$ and a bimodal distribution of $θ_{Bn}$. We also use the Rankine-Hugoniot relations to quantify the properties of the shock downstream. Our results provide a quantitative 3D magnetic structure condition of a coronal shock that produces a type II radio burst.
