太阳黑子颗粒光桥中的强对流
Vigorous convection in a sunspot granular light bridge
摘要:
光桥是太阳黑子中对流最显著的表现。最亮的代表是由看起来类似于颗粒的特征组成的颗粒光桥。深入研究的对流运动,温度分层,和磁场矢量和周围的光桥颗粒的目的是确定的相似性和差异,典型的安静的太阳颗粒。利用空间耦合反演技术分析了日出太阳光学望远镜的分光偏振数据,反演了光桥和静日颗粒的分层大气参数。中心热的上升气流周围的冷却器快速下降流达到10公里/秒,清楚地建立轻桥颗粒的对流性质。在近表面层中的这些颗粒的内部部分是无场的,并且被尖点状磁场配置覆盖。我们观察到磁场反转的迹象在快速下降流的位置。黑子附近的宁静太阳颗粒被一个从黑子向外放射状延伸的低洼天篷场所覆盖。安静的太阳和轻桥颗粒之间的相似之处,指出颗粒轻桥在底层对流区的深锚定。快速,超音速下降流是最有可能的组合的结果,由于辐射冷却到邻近的本影和事实,我们的样品更深的层,因为下降流是直接相邻的倾斜壁的威尔逊凹陷的光桥颗粒的对流。
英文摘要:
Light bridges are the most prominent manifestation of convection in sunspots. The brightest representatives are granular light bridges composed of features that appear to be similar to granules. An in-depth study of the convective motions, temperature stratification, and magnetic field vector in and around light bridge granules is presented with the aim of identifying similarities and differences to typical quiet-Sun granules. Spectropolarimetric data from the Hinode Solar Optical Telescope were analyzed using a spatially coupled inversion technique to retrieve the stratified atmospheric parameters of light bridge and quiet-Sun granules. Central hot upflows surrounded by cooler fast downflows reaching 10 km/s clearly establish the convective nature of the light bridge granules. The inner part of these granules in the near surface layers is field free and is covered by a cusp-like magnetic field configuration. We observe hints of field reversals at the location of the fast downflows. The quiet-Sun granules in the vicinity of the sunspot are covered by a low-lying canopy field extending radially outward from the spot. The similarities between quiet-Sun and light bridge granules point to the deep anchoring of granular light bridges in the underlying convection zone. The fast, supersonic downflows are most likely a result of a combination of invigorated convection in the light bridge granule due to radiative cooling into the neighboring umbra and the fact that we sample deeper layers, since the downflows are immediately adjacent to the slanted walls of the Wilson depression.
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