2017年07月11日:半人马座奥米茄星团的高动态範围影像-（Star Cluster Omega Centauri in HDR）--原图下载
Image Credit & Copyright: Mike O'Day
说明: 请观赏这颗我们银河系最大的恒星球。半人马奥米茄星团拥有挤在只有150光年直径体积内的将近1千万颗成员星，其中有许多比我们的太阳还高寿。这个星团是我们银河系银晕约200多个球状星团之中，最大与最明亮的一个。对大多数的星团而言，成员星的年龄和化学组成皆相仿，然而，谜样的奥米茄星团却有不同星族的恒星，各拥不同的年龄层和化学组成。因此，奥米茄星团有可能是小星系被我们银河併吞后，所残留下来的星系核。这幅主题影像之所以能显示这么多恒星，是因为它应用了高动态範围（HDR）成像技术，并组合不同曝光时间的多张照片。又名为NGC 5139的半人马奥米茄星团，位在南天的半人马座方向，离我们约有15,000光年远。
原文：
Image Credit & Copyright: Mike O'Day
Explanation: Behold the largest ball of stars in our galaxy.Omega Centauri is packed with about 10 million stars,many older than our Sun and packed within a volume of only about 150 light-years in diameter.The star cluster is the largest and brightest of 200 or so knownglobularclusters that roam thehalo of our Milky Way galaxy.Though most star clusters consist of stars with the same age andcomposition, the enigmatic Omega Cen exhibits the presence ofdifferentstellar populations with a spread of ages and chemical abundances.In fact,OmegaCen may be the remnant core of a small galaxy merging withthe Milky Way.The featured image shows so many stars because it merged different exposures with high dynamic range (HDR) techniques. Omega Centauri, also known as NGC 5139, lies about 15,000 light-years away toward the southern constellation of the Centaurus.
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