M13：大力神的大球状星团
(原标题: M13: The Great Globular Cluster in Hercules)
2022-08-04
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1716年，英国天文学家埃德蒙·哈雷（Edmond Halley）指出：“这只是一小块，但在天空宁静、月亮缺席的时候，肉眼就能看到它。”当然，M13现在被认为是大力神的大球状星团，是北方天空中最明亮的球状星团之一。像这样的清晰的望远镜图像揭示了这个壮观的星团中成千上万的恒星。在25000光年的距离上，星团的恒星聚集在一个直径150光年的区域。接近星团核心的100多颗恒星可以包含在一个边长只有3光年的立方体中。相比之下，离太阳最近的恒星距离太阳超过4光年。这张图像中记录的显著亮度范围跟随恒星进入密集的星团核心。中宽视场中的遥远背景星系包括左上角的NGC 6207。
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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 Globular Cluster in Hercules, one of the brightest globular star clusters in the northern sky. Sharp telescopic views like this one reveal the spectacular cluster's hundreds of thousands of stars. At a distance of 25,000 light-years, the cluster stars crowd into a region 150 light-years in diameter. Approaching the cluster core upwards of 100 stars could be contained in a cube just 3 light-years on a side. For comparison, the closest star to the Sun is over 4 light-years away. The remarkable range of brightness recorded in this image follows stars into the dense cluster core. Distant background galaxies in the medium-wide field of view include NGC 6207 at the upper left.
© Joan Josep Isach Cogollos