美国宇航局（NASA）位于马里兰州格林贝尔特的戈达德太空飞行中心的研究人员发现了一种新的银河“化石”，可以揭示星系的演化。X射线勾勒出附近螺旋星系NGC 4945中巨大冷气体云的轮廓。大约500万年前，该星系中央超大质量黑洞爆发后，这些气体似乎已经穿过了这个星系。
领导这项工作的戈达德天体物理学家金伯利・韦弗（Kimberly Weaver）称：“科学界对于星系如何演化一直存在争论。” “我们在几乎所有银河系大小的星系中心都发现了超大质量黑洞，一个悬而未决的问题是，与恒星形成的影响相比，它们的影响有多大。研究像 NGC 4945 这样的附近星系（我们认为我们正处于过渡时期）有助于建立更好的模型来了解恒星和黑洞如何产生星系变化。”
NGC 4945 是位于南半人马座的一个活跃星系，距离我们约 1300 万光年。NGC 4945 是一个星暴星系，这意味着它形成恒星的速度比我们的星系高得多。科学家估计，它每年产生的质量相当于 18 颗类似太阳的恒星，几乎是银河系的三倍。几乎所有的恒星形成都集中在星系的中心。星暴事件会持续 10 到 1 亿年，只有当制造新恒星的原材料耗尽时才会结束。
英语如下：
“News Title: NASA Discovers New Galaxy ‘Fossil’ Revealing Myster”News Title: NASA Discovers New Galaxy ‘Fossil’ Revealing Mysteries of Galactic Evolution
Keywords: NASA discovery, galactic evolution, X-ray activity
News Content: Researchers at the Goddard Space Flight Center in Greenbelt, Maryland, part of NASA, have discovered a new type of galaxy ‘fossil’ that can reveal the evolution of galaxies. X-rays have outlined the contours of huge cold gas clouds in the nearby spiral galaxy NGC 4945. These gases seem to have passed through the galaxy about 5 million years after an explosion from the supermassive black hole at its center.
Leading the work, Goddard astrophysicist Kimberly Weaver said, “There has been a debate in the scientific community about how galaxies evolve.” “We have found supermassive black holes at the centers of almost all galaxies the size of our own, and one unresolved question is how much their influence compares to that of star formation. Studying nearby galaxies like NGC 4945 (which we think are in transition) helps build better models for understanding how stars and black holes produce galactic changes.”
NGC 4945 is an active galaxy located in Centaurus Auriga, about 13 million light-years away from us. NGC 4945 is a starburst galaxy, meaning it forms stars much faster than our own galaxy. Scientists estimate that it produces mass equivalent to 18 sun-like stars per year, nearly three times that of the Milky Way. Almost all star formation is concentrated at the center of the galaxy. Starburst events can last from 10 to 100 million years, ending only when the raw materials for making new stars are exhausted.”
【来源】https://www.ithome.com/0/745/113.htm
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