天文學(xué)家已經(jīng)確定了銀河系的遙遠(yuǎn)邊緣

天文學(xué)家已經(jīng)確定了銀河系的遙遠(yuǎn)邊緣

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.

英國(guó)杜倫大學(xué)的天文學(xué)家對(duì)包括地球在內(nèi)的星系有了一項(xiàng)令人興奮的發(fā)現(xiàn)——確切地說(shuō)，他們終于發(fā)現(xiàn)了它的遠(yuǎn)緣。

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.

天體物理學(xué)家愛(ài)麗絲·迪森和她的同事們以附近的星系為參照，確定了銀河系的確切直徑為190萬(wàn)光年(誤差范圍為40萬(wàn)光年)。這是根據(jù)該團(tuán)隊(duì)發(fā)表在arXiv.org上的一篇論文得出的結(jié)論。arXiv.org是一個(gè)開(kāi)放獲取的檔案庫(kù)，收錄了來(lái)自學(xué)術(shù)界和科學(xué)家的數(shù)萬(wàn)篇文章。這項(xiàng)工作很重要，其原因包括它將幫助天文學(xué)家在未來(lái)做出更多發(fā)現(xiàn)。

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.

約翰霍普金斯大學(xué)(Johns Hopkins University)的天文學(xué)家羅斯瑪麗懷斯(Rosemary Wyse)在接受《科學(xué)新聞》(ScienceNews)雜志采訪時(shí)表示，這種新的銀河系測(cè)量方法應(yīng)該“有助于天文學(xué)家梳理出銀河系的其他特性”。“這是一個(gè)事實(shí)的參考，例如，我們?cè)搅私忏y河系的真實(shí)尺寸，它就會(huì)讓我們更好地理解什么(以及有多少)星系圍繞著它旋轉(zhuǎn)。”

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，已知有大約60顆恒星圍繞著銀河系，但預(yù)計(jì)這一新發(fā)現(xiàn)將導(dǎo)致更多的恒星被發(fā)現(xiàn)。

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.

研究小組通過(guò)計(jì)算機(jī)模擬來(lái)研究星系是如何形成的，并密切關(guān)注兩個(gè)星系在彼此旁邊的形成方式，比如我們的星系和它最近的鄰居。兩個(gè)星系的引力相互吸引，當(dāng)你走出像我們這樣的星系的暗暈時(shí)，小星系的速度就會(huì)下降。迪森團(tuán)隊(duì)的天文學(xué)家發(fā)現(xiàn)，銀河系附近的星系速度也出現(xiàn)了同樣的減速，這有助于他們精確定位銀河系的邊緣，距離銀河系中心約95萬(wàn)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.”

研究人員在他們的論文中寫道:“在許多對(duì)銀河系暈的分析中，它的外邊界是一個(gè)基本的限制。”通常，選擇是主觀的，但正如我們所爭(zhēng)論的，最好是定義一個(gè)物理和/或觀測(cè)動(dòng)機(jī)的外部邊緣。在這里，我們把潛在暗物質(zhì)分布的邊界與可觀測(cè)到的恒星暈和矮星系的數(shù)量聯(lián)系起來(lái)。”