[2021年09月08日:仙女大星系方向的深空影像-（The Deep Sky Toward Andromeda）--原图下载](https://apod.nasa.gov/apod/image/2109/M31WideField_Ziegenbalg_1400.jpg"
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Image Credit & License: Stefan Ziegenbalg
说明: 仙女大星系周围有什么天体？在太空远处的仙女大星系（M31），紧邻的区域内有数个小型伴星系，更外围有包括我们银河系在内的本星系群成员。在地球的天空中，近在我们银河系之内的星云，看似环拱在M31的周围，形成类似地球大气的水汽云包覆在月亮周边的景观。只不过，仙女大星系方向的气体云，通常过于昏暗而不得见。上面这张45度跨幅的主题影像，是仙女大星系方向有史以来最长曝光的较大範围影像之一。这幅摄于特定氢气辐射波段的影像，除了无比清晰的呈现这方向昏暗且陌生的星云之外，更捕捉到其他的景观。其中包括影像顶端的三角大星系（M33）；它是本星系群第三大的成员，也是人类肉眼所能见到的最遥远天体。在M33的右下方，则有银河系内的亮星奎宿九（Mirach）。这幅摄于德国．普尔斯尼茨镇的影像，是由在2018年至2021年之间所记录的数个长曝光数据组合而成。
原文：
Image Credit & License: Stefan Ziegenbalg
Explanation: What surrounds the Andromeda galaxy? Out in space, Andromeda (M31) is closely surrounded by several small satellite galaxies, and further out it is part of theLocal Group of Galaxies -- of which our Milky Way galaxy is also a member.On the sky, however, gas clouds local to our Milky Way appear to surround M31 -- not unlike how water clouds in Earth's atmosphere may appear to encompass our Moon. The gas clouds toward Andromeda, however, are usually too faint to see. Enter the featured 45-degree long image -- one of the deeper images yet taken of the broader Andromeda region.This image, sensitive to light specifically emitted by hydrogen gas, shows these faint and unfamiliar clouds in tremendous detail.But the image captures more. At the image top is the Triangulum galaxy (M33), the third largest galaxy in the Local Group and the furthest object that can be seen with the unaided eye. Below M33 is the bright Milky-Way star Mirach.The image is the digital accumulation of several long exposures taken from 2018 to 2021 from Pulsnitz, Germany.
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