人马三重星云

2021年04月26日

A Sagittarius Triplet
Image Credit & Copyright: Gabriel Rodrigues Santos

Explanation: These three bright nebulae are often featured on telescopic tours of the constellation Sagittarius and the crowded starfields of the central Milky Way. In fact, 18th century cosmic tourist Charles Messier cataloged two of them; M8, the large nebula below and right of center, and colorful M20 near the top of the frame. The third emission region includes NGC 6559, left of M8 and separated from the larger nebula by a dark dust lane. All three are stellar nurseries about five thousand light-years or so distant. Over a hundred light-years across the expansive M8 is also known as the Lagoon Nebula. M20’s popular moniker is the Trifid. Glowing hydrogen gas creates the dominant red color of the emission nebulae. But for striking contrast, blue hues in the Trifid are due to dust reflected starlight. The broad interstellarscape spans almost 4 degrees or 8 full moons on the sky.

Tomorrow’s picture: star shredder

人马三重星云
影像提供与版权: Gabriel Rodrigues Santos

说明: 用望远镜巡礼人马座和恒星群集的银河中心之时，这三个明亮星云经常是目光会聚的天体。其实远在十八世纪时，梅西耶就编录了其中的两个星云，它们分别是影像中右下方的大星云M8和顶缘附近的美丽M20。第三个发射星云是M8左方的NGC 6559，二者由一道黝黑尘埃带所分隔。这三个星云，都是距离在5千光年左右的恒星诞生区。跨幅超过100光年的庞大M8，亦名为礁湖星云，而M20常见的昵称是三叶星云。影像中，明亮氢气云发出的红光，是这些发射星云最主宰性的色泽，而三叶星云内高对比的泛蓝区域，则来自被尘埃所反射的星光。这片宽广的星际视野，横跨约4度（8个满月宽度）的天区。

明日的图片: star shredder