美丽的三叶星云

2021年8月12日

A Beautiful Trifid
Image Credit & Copyright: Mike Selby

Explanation: The beautiful Trifid Nebula is a cosmic study in contrasts. Also known as M20, it lies about 5,000 light-years away toward the nebula rich constellation Sagittarius. A star forming region in the plane of our galaxy, the Trifid does illustrate three different types of astronomical nebulae; red emission nebulae dominated by light from hydrogen atoms, blue reflection nebulae produced by dust reflecting starlight, and dark nebulae where dense dust clouds appear in silhouette. But the red emission region roughly separated into three parts by obscuring dust lanes is what lends the Trifid its popular name. Pillars and jets sculpted by newborn stars, below and left of the emission nebula’s center, appear in famous Hubble Space Telescope close-up images of the region. The Trifid Nebula is about 40 light-years across. Just too faint to be seen by the unaided eye, it almost covers the area of a full moon in planet Earth’s sky.

Tomorrow’s picture: a perfect spiral

美丽的三叶星云
影像提供与版权: Mike Selby

说明: 美丽的三叶星云是很独特的天体。又名为M20的三叶星云，位在星云密布的人马座方向，约5,000光年远之处。三叶星云是银河盘面的恒星形成区之一，同时拥有三种不同形态的天文星云，包括被氢原子辉光染红的发射星云、尘埃反射星光形成的泛蓝反射星云、以及本质为致密尘埃的剪影状暗星云。而在不透光尘埃带的切割下，这团明亮的发射星云裂成三片，为它得博得三叶星云的令名。在这团发射星云的中心左下方，可见到新恒星雕塑出的云柱及发出的喷流，它们因出现在哈伯太空望远镜为此区拍摄的多幅特写影像里而声名大噪。在地球的天空中，宽约40光年、张角与满月相近的三叶星云，比人类肉眼所能见的要稍暗一点。

明日的图片: a perfect spiral