Co-spatial velocity and magnetic swirls in the simulated solar photosphere
Co-spatial velocity and magnetic swirls in the simulated solar photosphere
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DOI：
10.1051/0004-6361/201936882
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发表时间：
2019-11
影响因子：
6.5
通讯作者：
Jiajia Liu;M. Carlsson;C. Nelson;R. Erd'elyi
中科院分区：
文献类型：
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作者：
Jiajia Liu;M. Carlsson;C. Nelson;R. Erd'elyi
上下文速度或强度漩涡现在已经被证明广泛存在于整个光球层和色球层。有人认为，这些事件可能有助于加热太阳上层大气，通过激发阿尔文脉冲，可以携带大量的能量。然而，它们激发的必要物理条件，即磁场与速度场同时空旋转，尚未得到验证。目标。我们的目标是了解光球速度漩涡是否存在同空间和同时间与光球磁漩涡，以证明漩涡和脉冲之间的联系。方法.自动涡流检测算法（ASDA）的光球水平速度和垂直磁场从一系列现实的数值模拟，使用辐射磁流体动力学（RMHD）代码彩虹。通过定义良好的相关指数（CI）的研究，进一步研究了检测到的速度和磁漩涡之间的空间关系。结果平均而言，在6 × 6 Mm−2的视场中，有1063个短寿命的光球速度漩涡（寿命大多小于20 s，平均半径为1037 km，旋转速度为102.5 km s−1），这意味着在太阳光球中的速度漩涡总数为101.06 × 107。超过80%的检测到的速度漩涡被认为是伴随着当地的磁浓度在晶间车道。平均而言，已发现约有71%的速度涡旋与光球磁涡旋共存，具有相同的旋转方向。结论.光球速度和磁场的同时间和同空间旋转提供了证据，证明光球漩涡激发阿尔文脉冲的约束条件得到了满足。
Context. Velocity or intensity swirls have now been shown to be widely present throughout the photosphere and chromosphere. It has been suggested that these events could contribute to the heating of the upper solar atmosphere, via exciting Alfvén pulses, which could carry significant amounts of energy. However, the conjectured necessary physical conditions for their excitation, that the magnetic field rotates co-spatially and co-temporally with the velocity field, has not been verified. Aims. We aim to understand whether photospheric velocity swirls exist co-spatially and co-temporally with photospheric magnetic swirls, in order to demonstrate the link between swirls and pulses. Methods. The automated swirl detection algorithm (ASDA) is applied to the photospheric horizontal velocity and vertical magnetic fields obtained from a series of realistic numerical simulations using the radiative magnetohydrodynamics (RMHD) code Bifrost. The spatial relationship between the detected velocity and magnetic swirls is further investigated via a well-defined correlation index (CI) study. Results. On average, there are ∼63 short-lived photospheric velocity swirls (with lifetimes mostly less than 20 s, and average radius of ∼37 km and rotating speeds of ∼2.5 km s−1) detected in a field of view (FOV) of 6 × 6 Mm−2, implying a total population of velocity swirls of ∼1.06 × 107 in the solar photosphere. More than 80% of the detected velocity swirls are found to be accompanied by local magnetic concentrations in intergranular lanes. On average, ∼71% of the detected velocity swirls have been found to co-exist with photospheric magnetic swirls with the same rotating direction. Conclusions. The co-temporal and co-spatial rotation in the photospheric velocity and magnetic fields provide evidence that the conjectured condition for the excitation of Alfvén pulses by photospheric swirls is fulfilled.