Magnetic reconnection resulting from flux emergence: implications for jet formation in the lower solar atmosphere?
Magnetic reconnection resulting from flux emergence: implications for jet formation in the lower solar atmosphere?
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DOI：
10.1051/0004-6361/201117515
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发表时间：
2011-09
影响因子：
6.5
通讯作者：
J. Y. Ding;J. Y. Ding;M. Madjarska;J. Doyle;Quanming Lu;K. Vanninathan;Zhenghua Huang
中科院分区：
文献类型：
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作者：
J. Y. Ding;J. Y. Ding;M. Madjarska;J. Doyle;Quanming Lu;K. Vanninathan;Zhenghua Huang
目标。我们的目标是研究太阳低层大气中喷射状特征的形成，例如色球层和过渡区，作为磁重联的结果。方法。使用 2.5D MHD 代码研究了在色球和过渡区域密度处发生并由磁通量出现触发的磁重联。初始大气是静态等温的，温度为2×10 4 K。初始磁场均匀且垂直。提供了两种具有不同磁场强度（25 G 和 50 G）的物理环境。在每种情况下，都会讨论两种子情况，其中环境具有不同的初始质量密度。结果。在磁场较弱（25 G）和较高的等离子体密度（Ne = 2× 10 11 cm -3 ）的情况下（对于典型的安静太阳色球层有效），将观察到温度为 2‐3× 10 4 K 且速度高达 40 km s -1 的等离子体射流。相反的情况是，电子密度较低（Ne = 2× 10 10 cm -3 ）的介质（即过渡区更典型）和 50 G 的更强磁场，产生视线速度高达∼90 km s -1 的上升流和 6× 10 5 K 的温度，即上过渡区 - 低日冕温度。仅在后一种情况下，低电晕 Feix 171 A 在射流中显示出与 Ov 增加相当的响应。结论。结果表明，磁重联可以成为驱动色球层和过渡区等离子体流出的有效机制。该模型可以通过改变磁场强度或电子密度（即大气中重新连接发生的位置）来重现一系列射流特征（如原纤维、针状体、热 X 射线射流或过渡区域射流）的温度和速度等特性。
Aims. We aim at investigating the formation of jet-like features i n the lower solar atmosphere, e.g. chromosphere and transition region, as a result of magnetic reconnection. Methods. Magnetic reconnection as occurring at chromospheric and transition regions densities and triggered by magnetic flux em ergence is studied using a 2.5D MHD code. The initial atmosphere is static and isothermal, with a temperature of 2× 10 4 K. The initial magnetic field is uniform and vertical. Two physical environments with different magnetic field strength (25 G and 50 G) are presented. In each case, two sub-cases are discussed, where the environments have different initial mass density. Results. In the case where we have a weaker magnetic field (25 G) and high er plasma density (Ne = 2× 10 11 cm −3 ), valid for the typical quiet Sun chromosphere, a plasma jet would be observed with a temperature of 2‐3× 10 4 K and a velocity as high as 40 km s −1 . The opposite case of a medium with a lower electron density (Ne = 2× 10 10 cm −3 ), i.e. more typical for the transition region, and a stronger magnetic field of 50 G, up-flows with line-of-sight v elocities as high as∼90 km s −1 and temperatures of 6× 10 5 K, i.e. upper transition region ‐ low coronal temperatures, are produced. Only in the latter case, the low corona Feix 171 A shows a response in the jet which is comparable to the Ov increase. Conclusions. The results show that magnetic reconnection can be an effi cient mechanism to drive plasma outflows in the chromosphere and transition region. The model can reproduce characteristics, such as temperature and velocity for a range of j et features like a fibril, a spicule, an hot X-ray jet or a transition region jet by changing either the magnetic field strength or the electro n density, i.e. where in the atmosphere the reconnection occurs.