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(双语)一些年轻的行星可能只是幻影

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一些年轻的行星可能只是幻影(图)
Some Young Planets May Be Mirages

by Ken Croswell     胡德良  

 

Planets emit no light of their own, so observers hunting for worlds orbiting other stars usually detect them indirectly. Now, one such technique has come under fire. The gravity of a planet circling a star in a dusty disk can carve gaps in the disk. But as researchers report online today in Nature, if the disk harbors as much gas as dust, the gas can cause the dust to clump into rings with sharp edges—even in the absence of planets. The best-known example, the scientists say, may be Fomalhaut, a bright star located just 25 light-years from Earth. Its dusty disk (red in the image; the white dot is the star) has a ring suggestive of a planet, which observers later claimed to see directly. However, that discovery has proven controversial, and the researchers say that if Fomalhaut's disk has gas—no one has yet seen any—then the star could have no planets at all.    行星自身并不释放光线,因此寻找环绕其他恒星的行星时,观测者们常常通过间接方式进行探测。现在,一种间接探测技术受到了挑战。在尘埃盘中,恒星周围的行星发出的引力可以将盘中划出间隙来。但是,研究人员今天在《自然》杂志上报道说:如果盘中的气体跟尘埃一样多,那么即使在没有行星的情况下,气体也会致使尘埃集结为有着明显边缘的环状。科学家们说,最为著名的例子可能就是北落师门系统。北落师门是距离地球仅仅25光年的一颗明亮的恒星,其尘埃盘(见图中红色部分,那个白点就是该恒星)有一个暗示着存在行星的环,后来观测者们声称直接观察到了那颗行星。然而,事实证明那次观察发现是有争议的。研究人员说,如果北落师门的尘埃盘中有气体——目前还没有人直接观察到气体——那么说明该恒星可能根本就没有行星。

 

        译自:美国《科学》杂志网站(10 July 2013, 1:00 PM

原著:Ken Croswell


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