自转的太阳

2020年8月19日

The Sun Rotating
Video Credit: SDO, NASA; Digital Composition: Kevin M. Gill

Explanation: Does the Sun change as it rotates? Yes, and the changes can vary from subtle to dramatic. In the featured time-lapse sequences, our Sun — as imaged by NASA’s Solar Dynamics Observatory — is shown rotating though an entire month in 2014. In the large image on the left, the solar chromosphere is depicted in ultraviolet light, while the smaller and lighter image to its upper right simultaneously shows the more familiar solar photosphere in visible light. The rest of the inset six Sun images highlight X-ray emission by relatively rare iron atoms located at different heights of the corona, all false-colored to accentuate differences. The Sun takes just under a month to rotate completely — rotating fastest at the equator. A large and active sunspot region rotates into view soon after the video starts. Subtle effects include changes in surface texture and the shapes of active regions. Dramatic effects include numerous flashes in active regions, and fluttering and erupting prominences visible all around the Sun’s edge. Presently, our Sun is passing an unusually low Solar minimum in activity of its 11-year magnetic cycle. As the video ends, the same large and active sunspot region previously mentioned rotates back into view, this time looking different.

Tomorrow’s picture: open space

自转的太阳
影片提供: SDO, NASA; 数字合成: Kevin M. Gill

说明: 太阳自转的同时也会边变脸吗？会的，而这些变化可介于微小与极为戏剧性之间。上面这幅由美国航太总署．太阳动态天文台拍摄的缩时影片，呈现了太阳在2014年整个月期间的自转景观。在左侧的大影像里，可见到紫外波段的太阳色球层。它右上角颜色较淡的小图，呈现了我们较熟悉可见光波段的光球层。而其余的五个嵌图，则突显在不同高度的日冕层中，含量相对稀少的铁原子在X射线波段辐射出的光，并渲染成不同的假色，以强调它们之间的差异。太阳自转周期略少于一个月，而且赤道区的自转最快。在影片开始不久，即可见到一个大型活跃黑子区旋入视野里。在这种活跃区内，微小的效应包括表面纹理和活跃区形状的变化。戏剧性的效应，则包括数量众多的闪焰和太阳边缘随处可见的日珥爆发。在约为11年的周期中，太阳目前正经历不寻常低活跃的极小期。在影片终结时，影片开头所见的那个大型活跃黑子区又转回来了，只不过，它看来很不一样。

明日的图片: open space