M 13 ： 海格力斯中的大球狀星團
M13: The Great Globular Cluster in Hercules
來源：R. Jay Gabany｜發表日期：2025-08-14
1716 年，英國天文學家埃德蒙-哈雷（Edmond Halley）指出："這只是一個小補丁，但在天空寧靜、月亮缺席的時候，肉眼就能看到它。當然，現在人們對 M 13 的認識已經不那麼謙虛了，它是位於海格力斯的大球狀星團，也是北天最亮的球狀星團之一。從望遠鏡的銳利視角可以看到這個壯觀的星團，其中有數十萬顆恆星。在 25000 光年的距離上，星團中的恆星擠在一個直徑為 150 光年的區域內。接近星團核心時，一個邊長僅為 3 光年的立方體中可以容納 100 多顆恆星。與我們附近的銀河系相比，距離太陽最近的恆星也在 4 光年以上。早期的球狀星團望遠鏡觀測者還注意到一個奇特的現象，那就是在星團中心下方，有三條間距約為 120 度的暗道匯聚在一起。 這種形狀被稱為 M 13 中的螺旋槳，很可能是從我們的視角觀察恆星分佈與密集的星團核心的偶然光學效應。
原文：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.
※ 本文由萌芽機器人自動轉貼自每日一天文圖（Astronomy Picture of the Day，APOD），原文為英文，正體中文是透過 DeepL 翻譯及 OpenCC 進行自動處理，內容僅供參考，若有任何錯誤之處還請見諒！
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