螺旋星系NGC 1398的环状和棒状结构
(原标题: Rings and Bar of Spiral Galaxy NGC 1398)
2023-07-12
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为什么一些螺旋星系的中心有一个环？螺旋星系NGC 1398不仅有一个由珍珠般的恒星、气体和尘埃组成的环围绕着它的中心，而且在它的中心还有一个由恒星和气体组成的棒状结构，螺旋臂在更远的地方看起来像缎带。这张来自智利El Sauce天文台的深度图像以令人印象深刻的细节展示了这个巨大的螺旋星系。NGC 1398距离地球约6500万光年，这意味着我们今天看到的光在恐龙从地球上消失时离开了这个星系。这个上镜的星系是用小型望远镜朝炉座（天炉座）方向看到的。中心附近的环可能是恒星形成的密度波，要么是由与另一个星系的引力相遇引起的，要么是由星系自身的引力不对称引起的。
查看原文解释
Why do some spiral galaxies have a ring around the center? Spiral galaxy NGC 1398 not only has a ring of pearly stars, gas and dust around its center, but a bar of stars and gas across its center, and spiral arms that appear like ribbons farther out. The featured deep image from Observatorio El Sauce in Chile shows the grand spiral galaxy in impressive detail. NGC 1398 lies about 65 million light years distant, meaning the light we see today left this galaxy when dinosaurs were disappearing from the Earth. The photogenic galaxy is visible with a small telescope toward the constellation of the Furnace (Fornax). The ring near the center is likely an expanding density wave of star formation, caused either by a gravitational encounter with another galaxy, or by the galaxy's own gravitational asymmetries.