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Thank your lucky stars you live in a relatively peaceful corner of the galaxy. Astronomers have found six large planets whose off-kilter orbits suggest that they crashed through their solar systems, swallowing any smaller planets that got in their way. The findings indicate that solar system formation is often disorderly and unpredictable, and that some potential cousins of Earth may have been destroyed in the chaos. |
多亏我们的幸运之星，我们生活在银河系一个相对平静的角落里。天文学家们发现了六颗巨大的行星，不规则的轨道表明它们在其恒星系统内发生碰撞，吞没了所有挡住去路的较小行星。该发现说明，恒星系统的形成通常是混乱而不可预测的，而且一些潜在的类地行星可能在这种混乱之中遭到毁灭。 |
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Astronomers have long thought that the formation of a star and its solar system was straightforward. A large cloud of gas and dust begins to congeal gravitationally, starts rotating, and eventually flattens into an object called a protostellar disk. That rotation dictates the future spin of the sun and the orbit of its planets. This is essentially what happened in our own solar system. There can be irregularities, of course, such as the odd spin axis of Uranus, which for as-yet-unexplained reasons is nearly tilted on its side, and Pluto's odd orbit, which occasionally takes it inside the path of Neptune. But these oddballs are nothing compared with what astronomers are seeing with six newly discovered planets known as hot Jupiters. |
长期以来，天文学家们认为一颗恒星及其恒星系统是直接形成的。由气体和尘埃构成的巨大云团在引力的作用下开始凝缩，并且开始旋转，最终变平成为平面状物体，这种物体被称为原恒星盘。开始的旋转决定着恒星未来的旋转以及行星轨道的性质。这基本上就是我们太阳系所发生的情况。当然其中也会有不规则的现象，如天王星奇特的自转轴几乎是向一侧倾斜的，其原因至今仍然无法解释；再如冥王星的轨道很奇特，有时它会在海王星的轨道之内运行。但是这些奇怪的星球与天文学家们目前所观察到的情况根本无法相提并论。据了解，这六颗新发现的行星属于热木星。 |
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Hot Jupiters resemble our largest planet in size and composition, yet they orbit much closer to their stars, sometimes well within what would be the orbit of Mercury. But the newly discovered worlds add an extra twist: all orbit in the opposite direction from all of the other objects in their solar system (a so-called retrograde orbit), and all orbit at severe angles. |
在大小和构成成分上，热木星跟我们太阳系最大的行星类似，但是它们的轨道距其恒星要近得多，有时比水星的轨道距太阳还要近。这些新发现的星球又增加了一种额外的旋转：它们在轨道上运行的方向跟其所在的恒星系统内所有其他天体的运行方向相反（即所谓的“逆行轨道”），而且所有的轨道都有着明显的角度。 |
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The implications are twofold, a team of astronomers led by Andrew Collier Cameron of the University of St. Andrews in the United Kingdom reports today at a meeting of the Royal Astronomical Society in Glasgow in the U.K. First, objects at least as large as these planets, and probably larger, must have shoved them severely out of their original orbits, probably well above or below the plane of their solar system. The encounters hurtled the gas giants in toward their parent suns. Then, each star's gravity caught the errant planet and whipped it around in a highly irregular, tight, and retrograde orbit. During this period of irregularity, which may have lasted millions of years, any rocky inner world sitting in the path of the hot Jupiter and its new orbit would have been obliterated. |
今天，英国圣安德鲁斯大学的安德鲁·科利尔·卡梅伦带领着一组天文学家，在英国格拉斯哥举行的一次皇家天文学会会议上报道：该发现具有双重意义。首先，至少象这些行星这么大、甚至很可能更大的天体一定撞击过它们，使它们严重地偏离了原有的轨道，造成了其轨道明显地高于或低于恒星系统的平面。猛烈冲撞使这些巨型气态行星向内靠近了其主恒星。其次，每一颗恒星的引力都吸引着那颗漂游的行星，使其在极不规则的近围轨道上作逆向运行。这种不规则的时期可能已经持续了几百万年，在此期间，位于热木星原有轨道以及新轨道上的任何系内的岩石行星都有可能已遭毁灭。 |
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The finding "adds to the accumulating evidence that the pathways that bring these giant planets close to their parent stars are messy and chaotic," says planetary scientist Jonathan Fortney of the University of California, Santa Cruz. It also suggests that there's "an incredible diversity in the structure of planetary systems,” he says. |
加州大学圣克鲁兹分校的行星科学家乔纳森·福特尼说，该发现使不断积累起来的证据更加充分了，说明巨型行星靠近其主恒星的途径是混乱不堪的。他说，该发现还表明，行星系统在结构上存在令人难以置信的多样性。 |
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These new worlds imply that there's a "dramatic and exciting process of gravitational billiards" at work, agrees astrophysicist Alan Boss of the Carnegie Institution of Washington in Washington, D.C. The finding lends credence to the idea that some gas giants in nascent solar systems “have to fight it out among themselves to see what orbit they will win and occupy," says Boss, a process he likens to "battles for office space on university campuses." |
华盛顿卡内基研究院的天体物理学家艾伦·博斯同意上述观点，他表示，这些新星球的发现意味着它们经历了一个引人瞩目而且令人兴奋的“引力撞球游戏”过程。博斯说，该发现使人们相信：在新形成的恒星系统中，一些巨型气态行星不得不从同类行星中杀出一条路来，以确定将要争得和占有哪一条轨道。博斯将这个过程比喻成“在大学校园里争抢办公空间”。 |
