颠覆认知！我国科学家重绘银河系旋臂结构

据新华社，我国科学家日前提出对银河系旋臂形态的新认识：银河系由内部对称两旋臂和外部多条不规则旋臂组成，更像是一个普通多旋臂星系，而非之前被广泛接受的四条旋臂均从内到外的特殊形态。

Chinese astronomers have recently transformed our understanding of the spiral structure of the Milky Way. They determined that it is more like a common multiple-arm galaxy, rather than a special galaxy with four spiral arms extending from its inner parts to its outer parts.

记者从中国科学院获悉，该研究由中科院紫金山天文台研究员徐烨研究团队与中科院国家天文台团队合作完成，相关成果日前在国际学术期刊《天体物理学杂志》上发表。

壮观美丽的银河。图源：新华社

据介绍，宇宙中旋涡星系的形态主要分为宏象、多旋臂和絮状三种旋涡结构。在类银河系的多旋臂星系中，较为常见的是内部两旋臂和外部多旋臂的形态(约占83%)，四条旋臂均从内到外的形态是非常罕见的(约占2%)，而此前天文学界普遍认为银河系正是属于这后一种特殊形态。

Multiple-arm spiral galaxies are of an intermediate type. About 83 percent of such galaxies have an inner two-arm symmetry and several irregular arms in their outer parts. Only about 2 percent have four spiral arms extending to their outer regions, and astronomers previously believed that the Milky Way was of this special four-arm type.

“由于人类身处银河系中，多重结构在视线方向重叠，使得我们无法从“鸟瞰”角度直接观察银河系的形态。”徐烨介绍，研究团队综合利用目前所能获得的全部高精度天体测量数据，利用天体脉泽、年轻恒星和疏散星团等作为定位旋臂的“灯塔”，对银河系旋臂结构进行了重新描绘。

Astronomers from the Purple Mountain Observatory and the National Astronomical Observatories, both institutions under the Chinese Academy of Sciences, used all available high-precision astrometric data to trace and identify the spiral arms of the Milky Way.

　　重新绘制的银河系旋臂结构鸟瞰图。图源：中科院紫金山天文台供图

研究结果表明，银河系具有多旋臂形态，其内部由英仙臂和矩尺臂两条旋臂对称向外延伸，在外部分叉并形成半人马臂、人马臂、船底臂和本地臂等多条长而不规则的旋臂段。

The study, published in The Astrophysical Journal, shows that the Milky Way is a multiple-arm galaxy that has two-arm symmetry — the Perseus and Norma Arms — in its inner parts, which extend to outer parts and split into several long, irregular arms.

“这一结果使银河系看起来不再特殊。研究团队正在为将来更高精度的测量积极准备，希望最终揭开银河系旋臂结构的庐山真面目。”徐烨说。

"The result makes the Milky Way no longer look special. The research team is preparing for higher-precision measurements in the future, with the hope of finally uncovering the spiral structure of the Milky Way," said Xu Ye, a lead researcher at the Purple Mountain Observatory.

来源：新华社