M13：大力神的大球状星团
(原标题: M13: The Great Globular Cluster in Hercules)
2025-08-14
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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。接近星团核心时，一个边长仅3光年的立方体可以容纳100多颗恒星。与我们的邻居银河系相比，离太阳最近的恒星距离我们超过4光年。早期用望远镜观察这个巨大的球状星团的观测者也注意到，在这个星团中心的下方，有三条间距约为120度的暗带奇怪地汇聚在一起。这个形状被称为M13中的螺旋桨，从我们的角度来看，它很可能是恒星分布的偶然光学效应，而不是密集的星团核心。
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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 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 with our neighborhood of the Milky Way, the closest star to the Sun is over 4 light-years away. Early telescopic observers of the great globular cluster also noted a curious convergence of three dark lanes with a spacing of about 120 degrees, seen here just below the cluster center. Known as the propeller in M13, the shape is likely a chance optical effect of the distribution of stars viewed from our perspective against the dense cluster core.
© R. Jay Gabany