The Biggest Diamond in the Known Universe Has Been Found.doc

1 5 JUNE 26 2014 THE BIGGEST DIAMOND IN THE KNOWN UNIVERSE HAS BEEN FOUND POSTED BY MICHAEL LEMONICK The 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 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 it s the corpse of a star that once looked very much like the sun lying nine hundred or 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 week s Astrophysical Journal told me that the star s invisibility is a key part of 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 so 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 subcategory of neutron star The first pulsar was found in 1968 and hundreds have been discovered since then A normal pulsar s 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 phenomenon L G M for little green men The bleeps from this pulsar known as PSR J2222 0137 aren t 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 PSR 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 more 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 were able to show the orbit is circular so it couldn t 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 it s the remnant of what was once an ordinary star but not one massive enough to explode Instead it simply puffed off its outer layers and shrank exactly 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 however even a dim white dwarf should have been visible The fact that they still can t see it suggests to Kaplan that it must be unusually cool no 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 temperature given the density of a white dwarf those elements should have crystallized Another name for crystallized carbon is diamond 3 5 The oxygen would have crystallized too so this object wouldn t necessarily be pure diamond But when you re talking about a sun s worth of diamond that hardly matters Kaplan and his team haven t given up on actually seeing the still unnamed object We re going to try with the Hubble Space Telescope he said If they can manage it they might be able to say more about the thing s structure and precise chemical composition If they can t they may be out of luck These things are probably very rare he said There are probably others out there but they re 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 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 天体物理学杂志 Astrophysical Journal 本周研究课题的第一作者 他告诉我 这颗恒星的不可见性是我们推测其存 在的重要环境依据 Kaplan解释道 证明这颗钻石存在的第一步证据是发现了一颗中子星 而这颗中子星 本身是一颗恒星的外壳 这颗恒星燃烧殆尽后爆炸坍塌 进而形成一种长度可以横跨 曼哈顿岛的物质 中子星密度很大 一勺中子星物质的质量可以重达1000万吨 而且 它的旋转速度极快 白天 时间只能持续几千分之一秒 随着中子星高速旋转 星体就会发射出脉冲无线电波 而天文学家可以通过无线电天 文望远镜检测到这种电波 并误以为它是一颗脉冲星 中子星的一种 第一颗脉冲 星于1968年发现 随后又发现了数百颗脉冲星 一颗正常脉冲星发射的电波非常有规 律 起初天文学家误以为那是人造电波 当他们弄清事情真相后 科学家才将这种现 象命名为 L G M 即 小绿人 little green man 5 5 而这颗编号为PSR J2222 0137的脉冲星发射的电波并不完全规律 但它加速和减速的节奏倒比较规律 Kaplan 和他的同事由此得知有物体正在围绕这颗中子星运动 而来自这一物体的重心引力正 在将这颗PSR J2222 0137脉冲星轻轻拉向地球 又拉离地球 如此循环往复 迫使脉冲星发出的电波相互 重叠 通过极其仔细地测量脉冲波的变化 天文学家们可以计算出这一不可见物体究竟有多 重 结果证明 其重量比太阳大5 这一物体应该是颗普通恒星 但这样一来 天 文学家应该轻而易举就能观测到才对 它也有可能是第二个中子星 但在这种情况下 恒星爆炸