M94：双环星系
(原标题: M94: A Double Ring Galaxy)
2023-06-07
浏览次数: 12
大多数星系都没有恒星和气体环——为什么M94有两个？首先，螺旋星系M94的核心周围有一个由新形成的恒星组成的内环，这不仅使它具有不寻常的外观，而且还具有强烈的内部发光。一个主要的起源假说认为，一个被称为棒状结构的细长的恒星结在M94中旋转，并在这个内环中产生了恒星形成的爆发。观测还发现了另一个环，一个外环，它更暗，颜色不同，不是封闭的，相对复杂。目前尚不清楚是什么导致了这个外环。如图所示，M94的总跨度约为45000光年，距离我们约1500万光年，可以用小型望远镜看到猎犬星座（Canes Venatici）。更多可用性：APOD现在可以通过Flipboard访问。
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Most galaxies don't have any rings of stars and gas -- why does M94 have two? First, spiral galaxy M94 has an inner ring of newly formed stars surrounding its nucleus, giving it not only an unusual appearance but also a strong interior glow. A leading origin hypothesis holds that an elongated knot of stars known as a bar rotates in M94 and has generated a burst of star formation in this inner ring. Observations have also revealed another ring, an outer ring, one that is more faint, different in color, not closed, and relatively complex. What caused this outer ring is currently unknown. M94, pictured here, spans about 45,000 light years in total, lies about 15 million light years away, and can be seen with a small telescope toward the constellation of the Hunting Dogs (Canes Venatici). More Availability: APOD now accessible via Flipboard.
© Brian Brennan