悬在太阳上方的三角形日珥

悬在太阳上方的三角形日珥

A Triangular Prominence Hovers Over the Sun
Image Credit & Copyright: Andrea Vanoni

Explanation: Why is there a triangle hovering over the Sun? Although the shape is unusual, the type of structure is not: it is part of an evolving solar prominence. Looping magnetic fields on the Sun channel the flow of energetic particles, sometimes holding glowing gaseous structures aloft for months. A prominence glows brightly because it contains particularly hot, dense, or opaque solar plasma. The surprising triangular structure occurred last week. Larger than our Earth, the iconic prominence was imaged by several solar photographers and documented by NASA’s Solar Dynamic Observatory to form and violently dissipate in about a day. The featured image was captured in a color of red light emitted strongly by hydrogen. Below, solar fibrils carpet the Sun’s chromosphere, while the background sky is so faint in comparison that no stars are visible. Our Sun’s surface has been quite active this year.

Tomorrow’s picture: Moon sisters

悬在太阳上方的三角形日珥
影像提供与版权: Andrea Vanoni

说明: 为何有个三角形悬在太阳的上方？虽然它的形状不寻常，但这种结构却颇为常见，因为它就是不断演化的日珥。太阳表面的环状磁场会导引高能粒子的流动，有时也会拘束发光气体，并让它悬浮在空中达数个月之久。日珥之所以很明亮，则是因为它的内部有极为炽热、密度高到不透光的太阳电浆/等离子体。这个出现在上星期的吸睛三角日珥，其实比地球大。这个从形成到爆发大约只有1天就消失的日珥，除了由几位太阳摄影者为它留下影像之外，也由美国国家航空航天局的太阳动态观测卫星加以记录。这幅主题影像摄于明亮的氢 红光波段。在日珥的下方，可见到形似绒毛地毯的太阳色球层，而背景天空则极为昏暗，看不到任何星星。最后，今年的太阳表面格外的活跃。

明日的图片: Moon sisters