NUMERICAL STUDY ON IN SITU PROMINENCE FORMATION BY RADIATIVE CONDENSATION IN THE SOLAR CORONA
NUMERICAL STUDY ON IN SITU PROMINENCE FORMATION BY RADIATIVE CONDENSATION IN THE SOLAR CORONA
复制标题
DOI：
10.1088/0004-637x/806/1/115
复制
发表时间：
2015-04
期刊：
影响因子：
--
通讯作者：
T. Kaneko;T. Yokoyama
中科院分区：
文献类型：
--
作者：
T. Kaneko;T. Yokoyama
我们提出了一个反极性日冕的原位形成模型，并用自洽的2.5维MHD模拟进行了验证，包括沿磁场的热传导和光学薄层辐射冷却。该模型使我们能够通过辐射凝聚在磁绳内形成冷密的等离子体云，这被认为是一个反极性日冕。辐射凝结是由磁拓扑结构的变化触发的，即从切变的拱形磁场形成磁通绳，以及由于捕获在磁通绳内的致密等离子体而引起的热不平衡。磁绳是通过在拱廊场地上施加收敛和剪切运动而产生的。当足点运动处于反剪切方向或加热与局部密度成正比时，磁绳内部的热态变得以冷却为主，导致辐射凝结。通过控制凝结温度，我们研究了温度与日冕密度之间的关系，并推导出了这种关系的标度公式。这个公式表明，所提出的模型再现了观测到的日冕密度，它比日冕密度大10-100倍。此外，将我们的模拟结果与太阳动力学观测站大气成像组件滤光片的响应函数相结合，合成的极端紫外线辐射的时间演化与在原位凝聚过程中观测到的多波长极端紫外线辐射之间的时间和空间强度漂移相一致。
We propose an in situ formation model for inverse-polarity solar prominences and demonstrate it using self-consistent 2.5 dimensional MHD simulations, including thermal conduction along magnetic fields and optically thin radiative cooling. The model enables us to form cool dense plasma clouds inside a flux rope by radiative condensation, which is regarded as an inverse-polarity prominence. Radiative condensation is triggered by changes in the magnetic topology, i.e., formation of the flux rope from the sheared arcade field, and by thermal imbalance due to the dense plasma trapped inside the flux rope. The flux rope is created by imposing converging and shearing motion on the arcade field. Either when the footpoint motion is in the anti-shearing direction or when heating is proportional to local density, the thermal state inside the flux rope becomes cooling-dominant, leading to radiative condensation. By controlling the temperature of condensation, we investigate the relationship between the temperature and density of prominences and derive a scaling formula for this relationship. This formula suggests that the proposed model reproduces the observed density of prominences, which is 10–100 times larger than the coronal density. Moreover, the time evolution of the extreme ultraviolet emission synthesized by combining our simulation results with the response function of the Solar Dynamics Observatory Atmospheric Imaging Assembly filters agrees with the observed temporal and spatial intensity shift among multi-wavelength extreme ultraviolet emission during in situ condensation.