2025年7月22日
Double Detonation Supernova
Image Credit: ESO, P. Das et al.; Background stars (NASA/Hubble): K. Noll et al.
Explanation: Can some supernovas explode twice? Yes, when the first explosion acts like a detonator for the second. This is a leading hypothesis for the cause of supernova remnant (SNR) 0509-67.5. In this two-star system, gravity causes the larger and fluffier star to give up mass to a smaller and denser white dwarf companion. Eventually the white dwarf‘s near-surface temperature goes so high that it explodes, creating a shock wave that goes both out and in — and so triggers a full Type Ia supernova near the center. Recent images of the SNR 0509-67.5 system, like the featured image from the Very Large Telescope in Chile, show two shells with radii and compositions consistent with the double detonation hypothesis. This system, SNR 0509-67.5 is also famous for two standing mysteries: why its bright supernova wasn’t noted 400 years ago, and why no visible companion star remains.
Tomorrow’s picture: rock being vaporized
双响炮超新星
影像提供: ESO, P. Das et al.; Background stars (NASA/Hubble): K. Noll et al.
说明: 超新星能够爆炸两次吗？当然可以，由第一次爆炸充当引信点燃了第二次更剧烈的大爆炸，就会出现这样罕见的现象。这是天文学家对超新星残骸（Supernova remnant, SNR）0509-67.5，到底是如何形成的所提出的主要假说。在这个致密的双星系统中，其中较大质量的膨胀恒星，会透过重力作用将质量转移至一颗较小质量但密度更高的白矮星伴星。最终，当白矮星的表层物质不断累积，导致其温度升高到足以引发热核爆炸，首次爆炸所产生的冲击波同时向内外扩展，进一步在中心附近触发第二次更剧烈的爆炸，形成完整的Ia型超新星。最近来自智利的甚大望远镜(Very Large Telescope, VLT)所拍摄的主题影像显示，SNR 0509-67.5拥有两层结构相似的壳层，其大小与成分都与所谓的「双响炮」模型相符，进一步支持此假说。除此之外，SNR 0509-67.5还伴随着两个悬而未解的谜题：为何如此明亮的超新星事件在约400年前，并未被人类所记录？以及，原本的伴星是如何消失得无影无踪？
明日的图片: rock being vaporized
