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Milky Way
NGC 3842
NGC 4889
the journal Nature
At the core of our Milky Way galaxy lies a black hole. Like all black holes, its gravitational pull is so strong that it swallows anything that ventures too close — even light. It weighs in at four million times the mass of the sun. But that's nothing compared to what astronomers have discovered at the heart of two galaxies about 300 million light-years away. Those galaxies go by the names NGC 3842 and NGC 4889. And they host the most massive black holes ever observed. Each is about 10 billion times the mass of the sun. That's equivalent to 2,500 of the Milky Way's black holes. The discoveries were announced in the journal Nature. Of course, black holes emit no light, and they can't be seen directly. But the astronomers were able to measure the mass of the black holes with a bit of extragalactic detective work. The researchers tracked how the black holes' gravitational pull influenced the motions of nearby stars. It's a bit like the FBI talking to a suspect's neighbors to get information. Word from the neighbors in this case — don't loan the black holes anything. You'll never get it back.
在我们的银河系中心有个黑洞。像其它的黑洞一样,它的重力吸引力强大到足以吞噬任何靠近它的物体,甚至是光。它重达太阳质量的四百万倍。 但是和天文学家们发现的距离我们30亿光年的另外两个星系比较而言,我们银河系中的这个黑洞就不算什么了。这两个星系的名字被命名为NGC 3842 和 NGC 4889。它们形成的巨大黑洞曾被观察到过。每一个黑洞的质量都大约是太阳的10亿倍。相当于2500个银河系黑洞。这个发现已经发表在《自然》杂志上。 当然,没有光线能从黑洞射出来,并且它们也不能被直接观察到。然而天文学家们能用银河系外的探测工具推算出黑洞的质量。研究人员们追踪了黑洞对其周边恒星运动所受到的重力引力影响情况。这有点儿像FBI和嫌疑犯邻居谈话调查取证。不过,从黑洞的邻居那里问话----可得不到关于黑洞的任何情况。因为,你将永远得不到回答。 —John Matson -------------------------------by hyjtb