双鱼座的壳星系
(原标题: Shell Galaxies in Pisces)
2024-11-07
浏览次数: 21
这幅壮观的星系间天空景观描绘了Arp 227，这是一个来自1966年奇特星系图集的奇怪星系系统。Arp 227距离双鱼座约1亿光年，由中央上方和左侧突出的两个星系组成，壳星系NGC 474和它的蓝色螺旋形邻居NGC 470。NGC 474的外壳和恒星流很可能是潮汐特征，起源于10多亿年前开始的近距离引力碰撞中另一个较小星系的吸积。深图像右下角的大星系NGC 467，似乎也被微弱的壳和流包围着，这是另一个合并星系系统的证据。有趣的背景星系散布在这片区域周围，其中还包括尖尖的前景恒星。当然，这些恒星就在我们的银河系内。望远镜的视场跨度为25角分，在天空中接近1/2度。
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This spectacular intergalactic skyscape features Arp 227, a curious system of galaxies from the 1966 Atlas of Peculiar Galaxies. Some 100 million light-years distant within the boundaries of the constellation Pisces, Arp 227 consists of the two galaxies prominent above and left of center, the shell galaxy NGC 474 and its blue, spiral-armed neighbor NGC 470. The readily apparent shells and star streams of NGC 474 are likely tidal features originating from the accretion of another smaller galaxy during close gravitational encounters that began over a billion years ago. The large galaxy on the bottom righthand side of the deep image, NGC 467, appears to be surrounded by faint shells and streams too, evidence of another merging galaxy system. Intriguing background galaxies are scattered around the field that also includes spiky foreground stars. Of course, those stars lie well within our own Milky Way Galaxy. The telescopic field of view spans 25 arc minutes or just under 1/2 degree on the sky.
© George Williams