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Weighing the Milky Way is no easy task. It's not like you can just step outside the galaxy and place it on a humongous scale.
要测量银河系的重量并不简单。因为人们不可能走出银河系，然后把它放在一个巨型的称上。
Plus, most of the galaxy's heft is in invisible dark matter, which betrays its presence only through its gravitational pull. So astronomers have devised clever ways of inferring the mass of our galaxy by measuring how it pulls on smaller objects moving around it.
而且占了银河系大部分重量的是无形的暗物质，人们之所以能发现暗物质是因为它的引力暴露了身份。因此天文学家采用了一种聪明的办法来推断银河系的重量，即通过测量它如何牵引在其周围转动的行星。
A new estimate, based on its effect on the motion of a nearby dwarf galaxy, has the Milky Way a bit beefier than some past measurements that relied on the motions of massive stars. The study is in the Astrophysical Journal.
基于银河系对毗连的矮星系的引力作用，研究人员作出一项新的估计：银河系比过去的测量更强大。过去的测量是以大质量恒星的运动为基础。这项研究发表在《天体物理学杂志》上。
The researchers first used the Hubble Space Telescope to track the dwarf galaxy Leo I, which at 850,000 light-years away is one of the most distant of the satellite galaxies swarming around the Milky Way. Then they simulated galaxies able to host such an object. Turns out that anything less massive than one trillion suns is very unlikely. In fact, the researchers estimate that the Milky Way's dark matter has as much mass as 1.6 trillion suns. That's some pretty heavy-duty astrophysics.
研究人员首先使用哈勃太空望远镜来跟踪狮子座白矮星一号，它距离银河系85万光年，是围绕银河系运转的最远的卫星星系。之后他们模拟了这一过程。事实证明，银河系的重量不可能少于一万亿个太阳。实际上，研究人员估计银河系暗物质的质量相当于1.6万亿个太阳。这是非常重要的一项天体物理学研究。
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