论文标题
分离的冠状环的平衡
The Equilibrium of Coronal Loops Near Separatrices
论文作者
论文摘要
我们介绍了具有高度不对称的闭合冠状环的数值模型（Hydrad），具有近乎斑点的膨胀因子。选择此环的方法是为了模拟冠状磁通管，该冠状磁通管接近零点，就像在冠状射流或伪流式的粉丝表面下的最后一组闭环中一样。该循环在冠状零零附近有一个非常大的横截面。假定冠状加热是均匀且稳定的。虹吸管在模拟时间的4小时内建立了自身，从小区域的脚步流向较大区域的脚步，随着等离子体接近无效区域，高初始速度迅速下降。从观察上讲，这将转化为从植根于本地少数族裔极性的脚上的10 km s $^{ - 1} $的强度上流，而从粉丝表面的脚点上则在几个km s $ s $^{-1} $的顺序上，以及几乎附近的等离子体附近的等离子体。我们提出了两个加热速率的模型结果。此外，我们分析了NULL点拓扑结构的类似Hinode EIS观测值，该观察结果显示了血浆中相关的多普勒移位，与模拟良好相关的多普勒移位既可以沿散装速度的方向和幅度。我们讨论了结果对确定冠状磁场拓扑的含义。
We present numerical models from the field-aligned Hydrodynamics and Radiation Code (HYDRAD) of a highly asymmetric closed coronal loop with near-singular expansion factor. This loop was chosen to simulate a coronal magnetic flux tube that passes close to a null point, as in the last set of closed loops under the fan surface of a coronal jet or a pseudostreamer. The loop has a very large cross-section localized near the coronal null. The coronal heating was assumed to be uniform and steady. A siphon flow establishes itself within 4 hours of simulation time, flowing from the smaller-area footpoint to the larger-area footpoint, with high initial speeds dropping rapidly as the plasma approaches the null region. Observationally, this would translate to strong upflows on the order of 10 km s$^{-1}$ from the footpoint rooted in the localized minority polarity, and weak downflows from the fan-surface footpoint on the order of a few km s$^{-1}$, along with near stationary plasma near the null region. We present the model results for two heating rates. In addition, we analyzed analogous Hinode EIS observations of null-point topologies, which show associated Doppler shifts in the plasma that correlate well with the simulation results in both direction and magnitude of the bulk velocity. We discuss the implications of our results for determining observationally the topology of the coronal magnetic field.
