171228期:星系物质循环往复的仙后座A

星系物质循环往复的仙后座A

我们银河系的大质量恒星,一生绚烂多姿。它们诞生于巨大的宇宙云气塌缩,塌缩后的核熔炉点燃并制造出位于它们核心的重元素。当核燃料经过数百万年的燃烧用尽后,恒星发生爆炸,把大量物质抛回星际空间并由此形成新的恒星。

上图中是仙后座A的超新星扩张碎片云,它正处于恒星生命的最后阶段。孕育了此超新星的爆炸所产生的闪光,出现在350年前的地球上空,然而事实上,这束光在宇宙中旅行了11,000年才最终得以被我们所见。

这张钱德拉X射线天文台观测到的卫星影像,经过染色,呈现出仙后座A中遗存的炽热的丝和结。影像以不同的色泽表现不同元素散发的高能辐射——矽辐射为红色,硫辐射为黄色,碳辐射为绿色,铁辐射为紫色,仍在扩张的爆炸激波构成了泛蓝的外环,这些色彩可以帮助天文学家探索我们银河的星系物质是如何循环往复的。

这张清晰的X光影像,按照仙后座A的预估距离测算,涵盖了约30光年的区域。影像中心附近的亮斑,是大质量恒星的核在坍塌后留下的中子星(一种密度巨大的天体)。

译:银河说翻译组 华夫饼喝酸奶

Recycling Cassiopeia A
Image Credit: NASA, CXC, SAO

Explanation: Massive stars in our Milky Way Galaxy live spectacular lives. Collapsing from vast cosmic clouds, their nuclear furnaces ignite and create heavy elements in their cores. After a few million years, the enriched material is blasted back into interstellar space where star formation can begin anew. The expanding debris cloud known as Cassiopeia A is an example of this final phase of the stellar life cycle. Light from the explosion which created this supernova remnant would have been first seen in planet Earth’s sky about 350 years ago, although it took that light about 11,000 years to reach us. This false-color Chandra X-ray Observatory image shows the still hot filaments and knots in the Cassiopeia A remnant. High-energy emission from specific elements has been color coded, silicon in red, sulfur in yellow, calcium in green and iron in purple, to help astronomers explore the recycling of our galaxy’s star stuff – Still expanding, the blast wave is seen as the blue outer ring. The sharp X-ray image, spans about 30 light-years at the estimated distance of Cassiopeia A. The bright speck near the center is a neutron star, the incredibly dense, collapsed remains of the massive stellar core.

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