Formation of a penumbra in a decaying sunspot
Formation of a penumbra in a decaying sunspot
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DOI：
10.1051/0004-6361/201321314
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发表时间：
2013-03
影响因子：
6.5
通讯作者：
R. Louis;S. Mathew;K. Puschmann;C. Beck;H. Balthasar
中科院分区：
文献类型：
--
作者：
R. Louis;S. Mathew;K. Puschmann;C. Beck;H. Balthasar
背景：半影是太阳黑子的一个重要特征，其形成与亚光球磁场的性质有着复杂的关系。目标：我们研究衰变太阳黑子中半影的形成，并将其特性与原黑子形成过程中所见的特性进行比较。方法：从 Hinode 上的分光偏振计获得了 NOAA 11283 活动区域的高分辨率分光偏振观测结果。这些数据还补充了来自日震和磁成像仪的高节奏连续强度全盘滤波图、视线磁图和多普勒图。结果：衰变太阳黑子中半影的形成发生在太阳黑子与磁性碎片/孔隙合并之后，磁性碎片/孔隙最初形成于靠近新兴通量区域的安静太阳中。首先，在合并位置附近形成了一组较小的半影细丝，其强度为 1.2 I_QS，上升流为 4 km/s，寿命为 10 小时。在这些细丝的衰变过程中，在合并的位置形成了更大的半影部分。这些新细丝的特点是 6.5 km/s 的近超音速下流，近 3 小时后变为常规的 Evershed 流。结论：孔隙与衰变太阳黑子的合并为太阳黑子中形成半影提供了足够的磁通量。新兴的通量区域可能在这一过程中发挥了决定性作用，因为形成发生在合并的位置，而不是在太阳黑子的另一侧。
Context : Penumbrae are an important characteristic of sunspots, whose formation is intricately related to the nature of sub-photospheric magnetic fields. Aims : We study the formation of a penumbra in a decaying sunspot and compare its properties with those seen during the development of a proto-spot. Methods : High-resolution spectropolarimetric observations of active region NOAA 11283 were obtained from the spectro-polarimeter on board Hinode. These were complemented with full-disk filtergrams of continuum intensity, line-of-sight magnetograms, and dopplergrams from the Helioseismic and Magnetic Imager at high cadence. Results : The formation of a penumbra in the decaying sunspot occurs after the coalescence of the sunspot with a magnetic fragment/pore, which initially formed in the quiet Sun close to an emerging flux region. At first, a smaller set of penumbral filaments develop near the location of the merger with very bright penumbral grains with intensities of 1.2 I_QS, upflows of 4 km/s, and a lifetime of 10 hr. During the decay of these filaments, a larger segment of a penumbra forms at the location of the coalescence. These new filaments are characterized by nearly supersonic downflows of 6.5 km/s that change to a regular Evershed flow nearly 3 hr later. Conclusions : The coalescence of the pore with the decaying sunspot provided sufficient magnetic flux for the penumbra to form in the sunspot. The emerging flux region could have played a decisive role in this process because the formation occurred at the location of the merger and not on the opposite side of the sunspot.