研究表明，银河系在数十亿年前吞并了另一个星系

For astronomers, discovering new worlds, stars and even entire galaxies is really only half the battle. Once discovered, explaining how new features of space formed and where they came from, often means extensive research and a bit of guesswork. A new research effort aimed at uncovering some of the secrets of how our home galaxy, the Milky Way, formed, astronomers believe they’ve found evidence of an ancient collision.

对于天文学家来说，发现新的世界、恒星甚至整个星系实际上只是战斗的一半。一旦发现，要解释空间的新特征是如何形成的以及它们来自何处，将意味着广泛的研究和设想。现在，在一项新的、旨在揭示我们银河系是如何形成的研究中，发现了古代碰撞的证据。

A new paper published in Nature Astronomy suggests that the Milky Way slammed into a smaller “dwarf” galaxy long ago, swallowing up a huge amount of mass and using it as fuel to churn out new stars for billions of years afterward.

一篇发表在《自然天文学》上的新论文表明，银河系很久以前撞上了一个较小的“矮”星系，吞没了大量的质量，并在随后的数十亿年里用它作为燃料大量产生新的恒星。

The research, which was made possible thanks to the high-powered Gaia space telescope, is based on the exact location and status of approximately a million stars in the Milky Way.

这项研究是基于银河系中大约100万颗恒星的确切位置和状态，多亏了高性能的盖亚太空望远镜才得以实现。

The scientists noted that the stars surveyed fall into one of two groups, one of which appears to be the result of an “accretion event,” which is believed to be evidence of a galaxy collision.

科学家们指出，被调查的恒星分为两组，其中一组似乎是“吸积事件”的结果，这被认为是星系碰撞的证据。

Being able to determine the ages of the stars using the Gaia telescope allowed the researchers to better simulate the early life of the Milky Way, supporting the theory that our galaxy swallowed up a smaller one.

利用盖亚望远镜能够确定恒星的年龄，使得研究人员能够更好地模拟银河系的早期生命，支持了我们的星系吞噬了一个较小星系的理论。

“The novelty of our work is that we have been able to assign precise ages to the stars that belong to the galaxies that merged and, by knowing these ages, when the merger took place,” Carme Gallart, lead author of the work, told AFP.

这项研究的主要作者Carme Gallart告诉法新社说:“我们的工作的新奇之处在于，我们已经能够确定合并星系的恒星的确切年龄，通过了解这些年龄，就可以确定合并发生的时间。”

“It’s a very gradual process—it’s not something like a car crash—it’s something that has an effect on the galaxy as a whole. It’s very massive so it happens slowly in human terms, not so slowly in cosmic time.”

“这是一个非常渐进的过程，它不像汽车碰撞，而是对整个银河系产生影响。而是对整个银河系产生影响的过程。它非常巨大，所以从人类的角度来看，它发生的很慢，而从宇宙的角度来看，就没那么慢了。”

It’s worth noting that this ancient collision isn’t the only one the Milky Way will experience, as astronomers already know that our galaxy is headed for a merger with the nearby Andromeda galaxy.

值得注意的是，这场古老的碰撞并不是银河系将经历的唯一一次碰撞，因为天文学家已经知道，我们的星系正朝着与邻近的仙女座星系合并的方向前进。

Thankfully that’s not expected to happen for another 4.5 billion years or so, so I wouldn’t worry too much about it.

值得庆幸的是，这在未来45亿年左右都不会发生，所以我们不必太担心。