天文学家已经确定了银河系的遥远边缘

天文学家已经确定了银河系的遥远边缘

Astronomers from Durham University in England have made an exciting discovery about the galaxy that includes Earth — specifically, they’ve finally found its far edge.

英国杜伦大学的天文学家对包括地球在内的星系有了一项令人兴奋的发现——确切地说，他们终于发现了它的远缘。

Using nearby galaxies as a guide, astrophysicist Alis Deason and her colleagues have determined the exact diameter of the Milky Way to be 1.9 million light-years (with a margin of error of 0.4 million light-years). That’s according to a paper from the team, posted at arXiv.org, which is an open-access archive of tens of thousands of articles from academics and scientists. And this work is important, for reasons that include the future additional discoveries it will help astronomers make.

天体物理学家爱丽丝·迪森和她的同事们以附近的星系为参照，确定了银河系的确切直径为190万光年(误差范围为40万光年)。这是根据该团队发表在arXiv.org上的一篇论文得出的结论。arXiv.org是一个开放获取的档案库，收录了来自学术界和科学家的数万篇文章。这项工作很重要，其原因包括它将帮助天文学家在未来做出更多发现。

Rosemary Wyse, an astronomer at Johns Hopkins University, told the publication ScienceNews about the new Milky Way measurement that it should “help astronomers tease out other galactic properties.” That’s a reference to the fact that, for example, the more we realize the true dimensions of the Milky Way, it gives us a better understanding of what (and how many) galaxies are revolving around it.

约翰霍普金斯大学(Johns Hopkins University)的天文学家罗斯玛丽怀斯(Rosemary Wyse)在接受《科学新闻》(ScienceNews)杂志采访时表示，这种新的银河系测量方法应该“有助于天文学家梳理出银河系的其他特性”。“这是一个事实的参考，例如，我们越了解银河系的真实尺寸，它就会让我们更好地理解什么(以及有多少)星系围绕着它旋转。”

Right now, about 60 are known to surround the Milky Way, but the expectation is that this new discovery will lead to the identification of more.

目前，已知有大约60颗恒星围绕着银河系，但预计这一新发现将导致更多的恒星被发现。

The team ran computer simulations to study how galaxies form and paid close attention to the way two galaxies form beside each other, like our galaxy and its nearest neighbor. Gravity from both galaxies pulls on each other and when you get out beyond the dark halo of a galaxy like ours, the velocities of small galaxies drops off. The astronomers from Deason’s team found that same kind of slowdown in galaxy speeds near the Milky Way, which helped them pinpoint the edge of our galaxy, at about 950,000 light-years from the center of the Milky Way.

研究小组通过计算机模拟来研究星系是如何形成的，并密切关注两个星系在彼此旁边的形成方式，比如我们的星系和它最近的邻居。两个星系的引力相互吸引，当你走出像我们这样的星系的暗晕时，小星系的速度就会下降。迪森团队的天文学家发现，银河系附近的星系速度也出现了同样的减速，这有助于他们精确定位银河系的边缘，距离银河系中心约95万光年。

“In many analyses of the Milky Way halo, its outer boundary is a fundamental constraint,” the researchers write in their paper. “Often, the choice is subjective, but as we have argued, it is preferable to define a physically and/or observationally motivated outer edge. Here we have linked the boundary of the underlying dark matter distribution to the observable stellar halo and the dwarf galaxy population.”

研究人员在他们的论文中写道:“在许多对银河系晕的分析中，它的外边界是一个基本的限制。”通常，选择是主观的，但正如我们所争论的，最好是定义一个物理和/或观测动机的外部边缘。在这里，我们把潜在暗物质分布的边界与可观测到的恒星晕和矮星系的数量联系起来。”