星系大战: M81与M82

2023年1月20日

Galaxy Wars: M81 and M82
Image Credit & Copyright: Andreas Aufschnaiter

Explanation: The two dominant galaxies near center are far far away, 12 million light-years distant toward the northern constellation of the Great Bear. On the right, with grand spiral arms and bright yellow core is spiral galaxy M81. Also known as Bode’s galaxy, M81 spans some 100,000 light-years. On the left is cigar-shaped irregular galaxy M82. The pair have been locked in gravitational combat for a billion years. Gravity from each galaxy has profoundly affected the other during a series of cosmic close encounters. Their last go-round lasted about 100 million years and likely raised density waves rippling around M81, resulting in the richness of M81’s spiral arms. M82 was left with violent star forming regions and colliding gas clouds so energetic that the galaxy glows in X-rays. In the next few billion years, their continuing gravitational encounters will result in a merger, and a single galaxy will remain. This extragalactic scenario also includes other members of the interacting M81 galaxy group with NGC 3077 below and right of the large spiral, and NGC 2976 at upper right in the frame. Captured under dark night skies in the Austrian Alps, the foreground of the wide-field image is filled with integrated flux nebulae. Those faint, dusty interstellar clouds reflect starlight above the plane of our own Milky Way galaxy.

Tomorrow’s picture: light-weekend

星系大战: M81与M82
图像提供与版权: Andreas Aufschnaiter

说明: 这二个大星系，位在北天的大熊座方向约1千2百万光年远之处。图像右方的星系，是拥有壮丽螺旋臂、泛黄核心、宽约100,000光年、亦名为波德星系的M81。位在图像左侧的，则是形如雪茄的不规则星系M82。于过去的十亿年之中，这两个星系不停透过引力进行缠斗。在一系列的近距离接近中，它们的引力对彼此都产生了重大的影响。于最近一轮持续约1亿年的缠斗中，引力互扰在M81的星系盘上，触发盘旋不息的密度波，并造就了M81壮观的螺旋臂。而在M82里，则出现产生大量恒星的猛暴恒星形成区及剧烈的星云碰撞，因而让它发出明亮的X射线辉光。在接下来的数十亿年之中，它们永不停歇的引力互扰，最后会让它们合并成单一个大星系。这片银河外部景观里，还可见到M81互扰星系群的其他成员，其中包括大螺旋星系右下方的NGC 3077，以及图像右上角的NGC 2976。这幅摄于奥地利阿尔卑斯山黝黑星空下的大视野图像里，前景挤满了共照耀星云（IFN）。这些位在我们银河系盘面上方的昏暗星际尘埃云，因淡淡的反射我们银河系盘面的星光而现踪。

明日的图片: light-weekend