171226期:大螺旋星系NGC1232

大螺旋星系NGC1232

星系之美不仅在于其可见部分,更在于其不可见的部分。由大望远镜捕捉到的大螺旋星系NGC1232即是一个很好的例子。可见部分是由数百万颗明亮的恒星和暗尘笼罩,它们陷入了围绕中心旋转的旋臂的重力漩涡之中。在这些旋臂上点缀着含有亮蓝恒星的疏散星团,而星团之中又点缀着布满星际尘埃的暗巷。难以看到却可以检测到的是数十亿颗暗淡的恒星和巨大的氢气,它们质量很高并共同支配着星系内部的动力。前沿的研究理论认为更多的物质虽不可见,但却以我们不知道的形式存在。这种普遍存在的暗物质在某种程度上可以被用来解释星系外部区域可见物质的运动。

译:银河说翻译组 Lee

Grand Spiral Galaxy NGC 1232
Image Credit: FORS, 8.2-meter VLT Antu, ESO

Explanation: Galaxies are fascinating not only for what is visible, but for what is invisible. Grand spiral galaxy NGC 1232, captured in detail by one of the Very Large Telescopes, is a good example. The visible is dominated by millions of bright stars and dark dust, caught up in a gravitational swirl of spiral arms revolving about the center. Open clusters containing bright blue stars can be seen sprinkled along these spiral arms, while dark lanes of dense interstellar dust can be seen sprinkled between them. Less visible, but detectable, are billions of dim normal stars and vast tracts of interstellar gas, together wielding such high mass that they dominate the dynamics of the inner galaxy. Leading theories indicate that even greater amounts of matter are invisible, in a form we don’t yet know. This pervasive dark matter is postulated, in part, to explain the motions of the visible matter in the outer regions of galaxies.

 

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