保护地球, 探索宇宙, 发现文明
2022年8月4日 M13: The Great Globular Cluster in Hercules Image Credit & Copyright: Joan Josep Isach Cogollos Explanation: In 1716, English astronomer Edmond Halley noted, “This is but a little Patch, but it shows itself to the naked Eye, when the Sky is serene and the Moon absent.” Of course, M13 is now less modestly recognized as the Great Glo...
2021年05月20日 M13: The Great Globular Cluster in Hercules Image Credit & Copyright: Martin Dufour Explanation: In 1716, English astronomer Edmond Halley noted, “This is but a little Patch, but it shews itself to the naked Eye, when the Sky is serene and the Moon absent.” Of course, M13 is now less modestly recognized as the Great Globular Clus...
2020 March 19 M13: The Great Globular Cluster in Hercules Image Credit & Copyright: Eric Coles and Mel Helm Explanation: In 1716, English astronomer Edmond Halley noted, “This is but a little Patch, but it shews itself to the naked Eye, when the Sky is serene and the Moon absent.” Of course, M13 is now less modestly recognized as the Great G...
2019 June 13 M13的颜色和星等 影像提供与版权: Tolga Gumusayak, Robert Vanderbei 说明: M13又称为武仙座大球状星团。在这个距离我们约25,000光年远的球形天体里，数十万颗成员星挤在宽约150光年的空间之内。这张图片左上角的M13之清晰彩色身影，是许多用望远镜巡天者很熟悉的景观。较特殊的，或许是右下使用同一组数据制作，带有更多资讯的M13之颜色-星等图。这种又称为赫罗（HR）图的图表，是以每颗成员星的视亮度相对于它的色指数作图。每颗星的色指数，定义为它透蓝光滤镜量测、以星等为单位的视亮度，减法红光滤镜的星等视亮度（B-R）。因为星色泛蓝的恒星温度较高，色泽偏红的恒星温度较低，所以在这种天文学图表上，色指数由左（高温）向右（低温）递增。在M13的赫罗图上，恒星...