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1、 1 / 5JUNE 26, 2014THE BIGGEST DIAMOND IN THE KNOWN UNIVERSE HAS BEEN FOUNDPOSTED BY MICHAEL LEMONICKThe biggest diamond ever found on Earth, known as the Cullinan diamond, weighed three thousand one hundred and six carats before it was cut, or about one and three-tenths pounds. The biggest diamond
2、ever found in the universe, whose discovery was announced this week, has no name, will never be cut, and weighs approximately a million trillion trillion pounds. This makes it as massive as the sun, and no wonder: its the corpse of a star that once looked very much like the sun, lying nine hundred o
3、r so light-years from Earth.Nobody has actually seen this gigantic diamond, not even through a telescope. David Kaplan, an astrophysicist at the University of Wisconsin-Milwaukee and the lead author of the study in this weeks Astrophysical Journal, told me that the stars invisibility is a key part o
4、f the circumstantial case for its existence.The first step to the proof, Kaplan explained, was the discovery of a neutron star, which itself is the husk of a star that burned up all its fuel, exploded, and then collapsed to form an object about as far across as Manhattan is long. A neutron star is 2
5、 / 5so dense that a teaspoonful of its substance would weigh ten million tons, and this one rotates so fast that its “day” lasts just a few thousandths of a second.Every time it goes around, it emits a pulse of radio waves that astronomers can detect with radio telescopes, making it a pulsar, a subc
6、ategory of neutron star. The first pulsar was found in 1968, and hundreds have been discovered since then. A normal pulsars radio bleeps are so perfectly regular that at first astronomers considered that the signal might be artificial; until they figured out what was going on, scientists called the
7、phenomenon “L.G.M.,” for “little green men.”The bleeps from this pulsar, known as PSR J2222-0137, arent absolutely regular; they speed up and slow down with a regular rhythm, which told Kaplan and his colleagues that something was orbiting it. The gravitational tug from that something was pulling PS
8、R J2222-0137 slightly toward the Earth, then slightly away, then toward again, forcing the beeps to pile up on each other, then pull back, and so on.By measuring the changes in pulses very carefully, the astronomers could calculate how massive the invisible something must be (about five per cent mor
9、e massive than the Sun, it turned out). The object could have been an ordinary star, but then the astronomers would have seen it easily. It could have been a second neutron star, but, in that case, the explosion that created it would have kicked it into an elongated orbit around its partner. “We wer
10、e able to show the orbit is circular, so it couldnt be a neutron star,” Kaplan told me.The only reasonable answer, they concluded, was that the invisible object is a white dwarf star. Like a neutron star, its the remnant of what was once an ordinary star, but not one massive enough to explode. Inste
11、ad, it simply puffed off its outer layers and shrankexactly the same thing that will happen to the sun in about five billion years. In this case, the star died eleven billion years ago, less than three billion years after the birth of the universe.At a distance of just nine hundred light-years, howe
12、ver, even a dim white dwarf should have been visible. The fact that they still cant see it suggests to Kaplan that it must be unusually coolno more than two thousand degrees, as opposed to about six thousand for the sun. “Most white dwarfs are made mostly of carbon and oxygen,” he said, and, at that
13、 temperature, given the density of a white dwarf, those elements should have crystallized. Another name for crystallized carbon is “diamond.” 3 / 5The oxygen would have crystallized, too, so this object wouldnt necessarily be pure diamond. But, when youre talking about a suns worth of diamond, that
14、hardly matters.Kaplan and his team havent given up on actually seeing the still-unnamed object. “Were going to try with the Hubble Space Telescope,” he said. If they can manage it, they might be able to say more about the things structure and precise chemical composition. If they cant, they may be o
15、ut of luck. “These things are probably very rare,” he said. “There are probably others out there, but theyre almost certainly too far away for us ever to see.”Photograph by Antonio Zambardino/Contrasto/Redux.KEYWORDS 4 / 5宇宙发现迄今最大钻石译者： 易小又 原作者： The New Yorker发表时间：2014-06-28 浏览量： 1147评论数：4挑错数：0库利南钻石（
16、Cullinan diamond）是迄今地球上发现的最大的一颗钻石，在被切割前，重达 3106克拉，约1.3英镑重。而在上星期发布的最新发现宇宙最大“钻石”，至今还未命名，而且永远不可能被人类切割。这颗钻石距离地球大约900光年，重量约1030英镑，几乎可以同太阳质量相媲美，难怪这颗死亡恒星一度看起来酷似太阳。2014.6.26宇宙发现迄今最大钻石Michael Lemonick库利南钻石（Cullinan diamond）是迄今地球上发现的最大的一颗钻石，在被切割前，重达3106 克拉，约1.3英镑重。而在上星期发布的最新发现宇宙最大“钻石”，至今还未命名，而且永远不可能被人类切割。这颗钻石距离地球大约900光年，重量约1030镑，几乎可以同太阳质量相媲美，难怪这颗死亡恒星一度看起来酷似太阳。没有人真正见过这颗巨型钻石，甚至使用望远镜也未亲眼目睹过。David Kaplan是威斯康星大学密尔沃基分校(University of Wisconsin-Milwaukee)的一名天体物理学家，同时也是天体物
