NGC 7331及其后方的天体

2023年9月14日

NGC 7331 and Beyond
Image Credit & Copyright: Ian Gorenstein

Explanation: Big, beautiful spiral galaxy NGC 7331 is often touted as an analog to our own Milky Way. About 50 million light-years distant in the northern constellation Pegasus, NGC 7331 was recognized early on as a spiral nebula and is actually one of the brighter galaxies not included in Charles Messier’s famous 18th century catalog. Since the galaxy’s disk is inclined to our line-of-sight, long telescopic exposures often result in images that evokes a strong sense of depth. The effect is further enhanced in this sharp image by galaxies that lie beyond the gorgeous island universe. The most prominent background galaxies are about one tenth the apparent size of NGC 7331 and so lie roughly ten times farther away. Their close alignment on the sky with NGC 7331 occurs just by chance. Lingering above the plane of the Milky Way, this striking visual grouping of galaxies is known to some as the Deer Lick Group.

Tomorrow’s picture: good morning moon

NGC 7331及其后方的天体
影像提供与版权: Ian Gorenstein

说明: 庞大美丽的螺旋星系NGC 7331，咸认是外观与我们银河系神似的星系。离我们约5千万光年远，位在北天飞马座方向的NGC 7331，很早就被归类为”螺旋星云”，然而，它也是18世纪著名的梅西耶星表未收录的较明亮星系之一。因为NGC 7331的盘面斜对着我们，望远镜的长曝光影像常带着很强的层次感。而在上面这幅清晰影像里，受到这个壮丽宇宙岛后方星系的衬托，这种层次感更加强烈。这些背景星系的视大小约莫是NGC 7331的10分之1，所以它们的距离也大约远上10倍。因此在影像里，它们看似和NGC 7331比邻纯是错觉。这个亦有鹿舔星系群之称的星系群，座落在银河盘面上方。 (Deer Lick Group 鹿舔星系群）

明日的图片: good morning moon