2026年2月6日
Supernova Remnant Cassiopeia A
Image Credit: NASA, ESA, CSA, STScI; D. Milisavljevic (Purdue University), T. Temim (Princeton University), I. De Looze (University of Gent)
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 only a few million years for the most massive stars, 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 supernova explosion that created this remnant would have been first seen in planet Earth’s sky about 350 years ago, although it took that light 11,000 years to reach us. This sharp NIRCam image from the James Webb Space Telescope shows the still-hot filaments and knots in the supernova remnant. The whitish, smoke-like outer shell of the expanding blast wave is about 20 light-years across. A series of light echoes from the massive star’s cataclysmic explosion are also identified in Webb’s detailed images of the surrounding interstellar medium.
Tomorrow’s picture: pixels in space
仙后座A超新星遗迹
影像提供: NASA, ESA, CSA, STScI; D. Milisavljevic (Purdue University), T. Temim (Princeton University), I. De Looze (University of Gent)
说明: 我们银河系中的大质量恒星拥有壮丽的生命历程。它们从巨大的宇宙云中坍缩而来，其核心的核融合反应炉点燃并产生重元素。对于质量最大的恒星而言，仅仅几百万年后，这些富含重元素的物质就会被抛射回星际空间，新的恒星形成过程可以再次开始。被称为仙后座A的不断膨胀的残骸云，正是恒星生命周期最后阶段的例子。大约350年前，地球的天空首次观测到形成这片遗迹的超新星爆发所发出的光，尽管这束光花了11000年才到达地球。詹姆斯·韦伯太空望远镜所拍摄这张清晰的NIRCam影像展示了超新星遗迹中仍然炙热的丝状结构和结点。扩展爆炸波的白色烟雾状外壳约有20光年宽。还可以在详细影像中识别出这颗大质量恒星剧烈爆炸产生的一系列光回波，显示了周围星际介质的复杂层次。
明日的图片: pixels in space
