2020年11月7日

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The Hercules Cluster of Galaxies
Image Credit & Copyright:
Howard Trottier

Explanation: These are galaxies of the Hercules Cluster, an archipelago of island universes a mere 500 million light-years away. Also known as Abell 2151, this cluster is loaded with gas and dust rich, star-forming spiral galaxies but has relatively few elliptical galaxies, which lack gas and dust and the associated newborn stars. The colors in this deep composite image clearly show the star forming galaxies with a blue tint and galaxies with older stellar populations with a yellowish cast. The sharp picture spans about 1/2 degree across the cluster center, corresponding to over 4 million light-years at the cluster’s estimated distance. Diffraction spikes around brighter foreground stars in our own Milky Way galaxy are produced by the imaging telescope’s mirror support vanes. In the cosmic vista many galaxies seem to be colliding or merging while others seem distorted – clear evidence that cluster galaxies commonly interact. In fact, the Hercules Cluster itself may be seen as the result of ongoing mergers of smaller galaxy clusters and is thought to be similar to young galaxy clusters in the much more distant, early Universe.

Tomorrow’s picture: a dark moon


武仙星系
影像提供与版权:
Howard Trottier

说明: 这些星系是一群离我们只有5亿光年远的宇宙岛,隶属武仙座星系团的成员。这个亦名为Abell 2151的星系团,拥有许多挤满气、尘埃恒星形成区的螺旋星系,但只有数量相对稀少且云气、尘埃和新诞生恒星缺如的椭圆星系。在这幅精彩的深空组合影像里,内部有恒星形成区的星系泛着蓝晕,而内部只有年老星群的星系则泛黄。这张清晰的影像涵盖了星系团中心约半度的天区,依星系团所在的距离估算,相当于是4百万光年的区域。带绕射芒的天体,是我们银河系内的较亮前景恒星,它们的星芒源自望远镜的镜片支架。在这片宇宙视野里,许多星系看似在​​互撞或合并,有些形状带点扭曲,显示星系团的成员星系之间经常互扰。事实上,武仙座星系团可视为是小型星系团合并的产物,因此咸认 它应该和遥远、很早期宇宙里的年轻星系团很类似。

明日的图片: a dark moon

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