Two Classes of Eruptive Events During Solar Minimum
Two Classes of Eruptive Events During Solar Minimum
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DOI：
10.1007/s11207-021-01845-x
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发表时间：
2021-03
期刊：
影响因子：
2.8
通讯作者：
P. Bhowmik;Anthony Yeates
中科院分区：
文献类型：
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作者：
P. Bhowmik;Anthony Yeates
在太阳极小期，太阳相对不活跃，在太阳表面观察到的太阳黑子很少。因此，我们观察到的高能事件，如太阳耀斑或日冕物质抛射（CME），这往往是与光球上的活动区域较少。尽管如此，我们的磁摩擦模拟在最低时期表明，太阳日冕仍然是动态演变的大尺度剪切速度在太阳表面上的响应。日冕的非势演化导致磁自由能和螺旋度的积累，并在爆发事件中周期性地释放。我们发现，这些事件分为两个不同的类：一组事件是由爆发和喷出的低洼日冕通量绳，他们可以解释的起源，偶尔CME在太阳极小期。另一组事件不是由低洼结构的不稳定性驱动的，而是由上覆剪切拱廊的喷发驱动的。这些可能与流光井喷或隐形日冕物质抛射有关。这两个类显着不同的磁通量和螺旋度通过外日冕边界脱落的量。我们还探讨了其他可测量的，如电流，开放的磁通量，自由能，日冕洞，和外模型边界上的磁场的水平分量在两类事件的变化。这项研究强调了了解太阳极小期日冕磁场动力学的重要性和必要性。
During solar minimum, the Sun is relatively inactive with few sunspots observed on the solar surface. Consequently, we observe a smaller number of highly energetic events such as solar flares or coronal mass ejections (CMEs), which are often associated with active regions on the photosphere. Nonetheless, our magnetofrictional simulations during the minimum period suggest that the solar corona is still dynamically evolving in response to the large-scale shearing velocities on the solar surface. The non-potential evolution of the corona leads to the accumulation of magnetic free energy and helicity, which is periodically shed in eruptive events. We find that these events fall into two distinct classes: One set of events are caused by eruption and ejection of low-lying coronal flux ropes, and they could explain the origin of occasional CMEs during solar minimum. The other set of events are not driven by destabilisation of low-lying structures but rather by eruption of overlying sheared arcades. These could be associated with streamer blowouts or stealth CMEs. The two classes differ significantly in the amount of magnetic flux and helicity shed through the outer coronal boundary. We additionally explore how other measurables such as current, open magnetic flux, free energy, coronal holes, and the horizontal component of the magnetic field on the outer model boundary vary during the two classes of event. This study emphasises the importance and necessity of understanding the dynamics of the coronal magnetic field during solar minimum.