2025年9月17日
Nebulas and Clusters in Sagittarius
Image Credit & Copyright: J. De Winter, C. Humbert, C. Robert & V. Sabet; Text: Ogetay Kayali (MTU)
Explanation: Can you spot famous celestial objects in this image? 18th-century astronomer Charles Messier cataloged only two of them: the bright Lagoon Nebula (M8) at the bottom, and the colorful Trifid Nebula (M20) at the upper right. The one on the left that resembles a cat’s paw is NGC 6559, and it is much fainter than the other two. Even harder to spot are the thin blue filaments on the left, from supernova remnant (SNR G007.5-01.7). Their glow comes from small amounts of glowing oxygen atoms that are so faint that it took over 17 hours of exposure with just one blue color to bring up. Framing this scene of stellar birth and death are two star clusters: the open cluster M21 just above Trifid, and the globular cluster NGC 6544 at lower left.
Tomorrow’s picture: that new comet
人马座中的星云与星团
影像提供与版权: J. De Winter, C. Humbert, C. Robert & V. Sabet; 文稿: Ogetay Kayali (MTU)
说明: 你能在这张图片中找出著名的天体吗？18世纪的天文学家查尔斯·梅西耶仅将其中两个天体编入他的星表：位于底部明亮的礁湖星云（M8），以及位于右上方色彩缤纷的三叶星云（M20）。左边那个看起来像猫爪的天体是NGC 6559，它比其他两个天体要暗淡得多。更难以辨识的是左边那些来自超新星遗迹（SNR G007.5-01.7）的细蓝色丝状结构。它们的光芒来自少量发光的氧原子，这些氧原子非常黯淡，以至于需要超过17小时的曝光，才能显现出蓝色。这幅描绘恒星诞生与死亡的场景中，还有两个星团：位于三叶星云上方的疏散星团 M21，以及位于左下方的球状星团 NGC 6544。
明日的图片: that new comet
