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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.
要測量銀河系的重量并不簡單。因為人們不可能走出銀河系，然后把它放在一個巨型的稱上。
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.
而且占了銀河系大部分重量的是無形的暗物質，人們之所以能發現暗物質是因為它的引力暴露了身份。因此天文學家采用了一種聰明的辦法來推斷銀河系的重量，即通過測量它如何牽引在其周圍轉動的行星。
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.
基于銀河系對毗連的矮星系的引力作用，研究人員作出一項新的估計：銀河系比過去的測量更強大。過去的測量是以大質量恒星的運動為基礎。這項研究發表在《天體物理學雜志》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.
研究人員首先使用哈勃太空望遠鏡來跟蹤獅子座白矮星一號，它距離銀河系85萬光年，是圍繞銀河系運轉的最遠的衛星星系。之后他們模擬了這一過程。事實證明，銀河系的重量不可能少于一萬億個太陽。實際上，研究人員估計銀河系暗物質的質量相當于1.6萬億個太陽。這是非常重要的一項天體物理學研究。
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