180110期:哈伯望远镜拍摄下的合并星系

NGC 2623:哈伯望远镜拍摄的合并星系  

当星系碰撞时,恒星会形成于何处?为了找出答案,天文学家使用哈伯太空望远镜对邻近合并的星系NGC 2623,进行高解析造影。分析这张及其他的哈伯望远镜影像,以及由史匹哲太空望远镜红外光XMM-牛顿望远镜在X射线、以及GALEX望远镜紫外光为星系NGC 2623所拍摄的影像,显示这两个原先分离的螺旋星系,如今紧密缠绕,而且两者的核心已合并成一个活跃星系核(AGN)。在上面这张主题影像的中心区及二侧清楚可见向外伸展的潮汐尾,恒星诞生活动正在进行中,但是更令人惊讶的是,在左上方远离核心的区域,却出现成群的明亮泛蓝恒星。星系碰撞可能需要数亿年的时间,并且需要几次重力破坏性的传递。别名为Arp 243的NGC 2623宽度则在50,000光年上下 位于巨蟹座大约2亿5000万光年远。重建原始的星系,了解星系合并如何发生,通常挑战性极大,但对于理解我们的宇宙是如何演化的却是极其重要的。

译:银河说翻译组  雪洋洋

NGC 2623: Merging Galaxies from Hubble
Image Credit: ESA/Hubble & NASA

Explanation: Where do stars form when galaxies collide? To help find out, astronomers imaged the nearby galaxy merger NGC 2623 in high resolution with the Hubble Space Telescope. Analysis of this and other Hubble images as well as images of NGC 2623 in infrared light by the Spitzer Space Telescope, in X-ray light by XMM-Newton, and in ultraviolet light by GALEX, indicate that two originally spiral galaxies appear now to be greatly convolved and that their cores have unified into oneactive galactic nucleus (AGN). Star formation continues around this core near the featured image center, along the stretched out tidal tails visible on either side, and perhaps surprisingly, in an off-nuclear region on the upper left where clusters of bright blue stars appear. Galaxy collisions can take hundreds of millions of years and take several gravitationally destructive passes. NGC 2623, also known as Arp 243, spans about 50,000 light years and lies about 250 million light years away toward the constellation of the Crab (Cancer). Reconstructing the original galaxies and how galaxy mergers happen is often challenging, sometimes impossible, but generally important to understanding how our universe evolved.

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