正在形成中的“第二地球”（图）
Astronomers See Second Earth in the MakingBy Ker Than 胡德良 译
Astronomers have spotted evidence of a second Earth being built around a distant star 424 light-years away. 天文学家们发现的证据表明：在424光年以外的一颗遥远恒星的周围，又一个地球正在形成。
Using NASA's Spitzer Space Telescope, astronomers have spotted a huge belt of warm dust swirling around a young star called HD 113766 that is just slightly larger than our sun. The dust belt, which scientists suspect is clumping together to form planets, is located in the middle of the star system's terrestrial habitable zone where temperatures are moderate enough to sustain liquid water. Scientists estimate there is enough material in the belt to form a Mars-sized world or larger.天文学家们利用美国航空航天管理局的斯必泽太空望远镜，发现了一个温暖的尘埃巨带正在围绕着一颗年轻的恒星旋转。该恒星叫做HD 113766，比太阳稍微大一些。科学家们认为，这个尘埃巨带正在聚集到一起，形成行星，而且其位置处于这个恒星系统可居住环带的中部，类似地球，温度适中，可支持液态水的存在。科学家们估计：在这个尘埃巨带中，具有足够的材料以形成一个象火星大小、或者更大一些的行星。At approximately 10 million years old, the star is just the right age for forming rocky planets, the researchers say. Their finding will be detailed in an upcoming issue of Astrophysical Journal.
研究人员们说，这颗恒星大约有1000万年的历史了，正是形成岩石行星的合适年龄。他们的发现将详细地记录在即将出版的一期《天体物理学杂志》上。"The timing for this system to be building an Earth is very good," said study team member Carey Lisse of the Johns Hopkins University Applied Physics Laboratory in Baltimore, Md.研究小组成员、马里兰州巴尔的摩约翰霍普金斯大学应用物理实验室的凯里·利斯指出：“就这个恒星系统来说，形成类地行星的时机非常合适。”If the star system were too young, the planet-forming disk would be full of gas, and it would be making gas-giant planets like Jupiter instead. If it were too old, Spitzer would have spotted rocky planets that had long ago formed.如果该恒星系统太年轻，这个正在形成行星的圆盘将充满气体，反而会形成类似木星的巨型气态行星。如果该恒星系统太古老，斯必泽太空望远镜所发现的就会是早已形成了的岩石行星。The star system also has the right mix of dusty materials in its disk to form an Earth-like planet, Lisse said.利斯说，该恒星系统圆盘中的各种尘埃物质也混合得恰到好处，拥有构成类地行星的条件。Using Spitzer's infrared spectrometer instrument, the team determined that the material around HD 113766 is more processed than the snowball-like stuff that makes up infant solar systems and comets, which are considered cosmic "refrigerators" because they contain pristine ingredients from the solar system's formative period. But it is also not as processed as the stuff found in mature planets and asteroids.研究小组利用斯必泽太空望远镜的红外分光仪测定：HD 113766周围的物质比构成幼年时期恒星系统和彗星的雪球状物质进化得更为超前，而雪球状物质被称为宇宙的“冷库”，因为其中包含恒星系统形成时期的原始组分。但是该恒星周围的物质却不如成熟行星和成熟小行星上的物质进化得超前。"The material mix in this belt is most reminiscent of the stuff found in lava flows on Earth," Lisse said. "I thought of Mauna Kea material when I first saw the dust composition in this system - it contains raw rock and it's abundant in iron sulfides, which are similar to fool's gold."“这个尘埃巨带中的混合物质使人想到地球上熔岩流中发现的物质，”利斯说，“第一次看见这个恒星系统中尘埃的组成成分时，我想起了夏威夷莫纳克亚山上的物质——其中包含原岩，富有含铁硫化物，类似于黄铁矿。”Earlier this year, scientists announced they had found evidence for one, and possibly two, already formed Earth-like planets around Gliese 581, a dim red star located only 20.5 light-years away. The possible planets, called Gliese 581c and Gliese 581d, are located at about the right distance from their star to support liquid water and life as we know it, but many more observations are needed to confirm this.今年早些时候科学家们宣称，他们发现的证据表明：有一颗，也可能是两颗已经形成的类地行星，在围绕着“格里斯581”旋转。“格里斯581”是一颗暗淡的红矮星，仅仅位于距地球20.5光年处。这两颗可能存在的类地行星一颗叫做“格里斯581 c”，另一颗叫做“格里斯581 d”。据我们了解，两颗行星到其恒星的距离基本合适，支持液态水和生命的存在。但是，要想对这一点加以验证，仍需要进行多次观测。To date, planet hunters have discovered more than 250 extrasolar planets, or "exoplanets." Most of the distant worlds, however, are giant gas planets several times the size of Jupiter.到目前为止，行星探测器已发现了250多个太阳系以外的行星，或称为“系外行星”。然而，遥远的行星中，绝大多数为巨大的气态行星，数倍于木星的大小。While life is known to exist only on our planet, the range of exoplanet types found so far has made astronomers increasingly confident that many worlds in our galaxy could be habitable. Finding Earth-like worlds in habitable zones is a first step toward the technically challenging task of discovering biology outside our solar system.尽管跟据了解只有我们这个行星上才会有生命，但是到目前为止所发现的系外行星的种类之多，使天文学家们越来越有理由相信：我们星系中的很多星球都有可能适合居住。在太阳系以外发现生物是一项具有技术挑战性的任务，而在适合居住的区域找到类地行星则是完成这项任务的第一步。
译自：http://www.livescience.com/space/
准备搬家。 咱们是没有机会了 咱们是没有机会了
启航 发表于 2012-5-6 18:53 http://www.lukeclub.com/images/common/back.gif
:lol :lol
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