RCW 86: 古超新星遗迹
RCW 86: Historical Supernova Remnant
Image Credit: CTIO/NOIRLab/DOE/NSF/AURA, T.A. Rector (Univ.of Alaska/NSF’s NOIRLab),
J. Miller (Gemini Obs./NSF’s NOIRLab), M. Zamani & D. de Martin (NSF’s NOIRLab)
Explanation: In 185 AD, Chinese astronomers recorded the appearance of a new star in the Nanmen asterism. That part of the sky is identified with Alpha and Beta Centauri on modern star charts. The new star was visible to the naked-eye for months, and is now thought to be the earliest recorded supernova. This deep telescopic view reveals the wispy outlines of emission nebula RCW 86, just visible against the starry background, understood to be the remnant of that stellar explosion. Captured by the wide-field Dark Energy Camera operating at Cerro Tololo Inter-American Observatory in Chile, the image traces the full extent of a ragged shell of gas ionized by the still expanding shock wave. Space-based images indicate an abundance of the element iron in RCW 86 and the absence of a neutron star or pulsar within the remnant, suggesting that the original supernova was Type Ia. Unlike the core collapse supernova explosion of a massive star, a Type Ia supernova is a thermonuclear detonation on a white dwarf star that accretes material from a companion in a binary star system. Near the plane of our Milky Way galaxy and larger than the full moon on the sky this supernova remnant is too faint to be seen by eye though. RCW 86 is some 8,000 light-years distant and around 100 light-years across.
Tomorrow’s picture: 10 days of Venus and Jupiter
RCW 86: 古超新星遗迹
图像提供: CTIO/NOIRLab/DOE/NSF/AURA, T.A. Rector (Univ.of Alaska/NSF’s NOIRLab),
J. Miller (Gemini Obs./NSF’s NOIRLab), M. Zamani & D. de Martin (NSF’s NOIRLab)
说明: 在公元185年，古中国天文学家记录了一颗出现在南门星官的新星。于现代的星图里，该天区大约在半人马座的南门二及马腹一附近。这颗连续数月肉眼可见的新星，目前咸认是人类最早的超新星观测记录。在上面这幅深空望远镜图像里，勉强可从繁星背景认出的发射星云RCW 86之纤细轮廓，据信就是这例恒星爆炸的遗迹。由智利.托洛洛山美洲天文台（CTIO）.宽视野暗能量相机所拍摄的这幅图像，则呈现了仍不断扩张、被爆炸震波所电离的气壳之完整面貌。摄于太空的图像显示，RCW 86内有大量的铁元素，不过遗迹里并无中子星（或波霎），因此这例超新星之分类可能是Ia。与大质量恒星的核坍缩超新星爆炸有别的是：Ia型超新星是双星系统里的白矮星，在吸积来自伴星的物质后所发生之热核爆炸。这个在天空的张角大于满月的超新星遗迹，位在银河的盘面附近，其亮度过于昏暗，因此肉眼不得见。跨幅约100光年的RCW 86，距离我们约有8,000光年远。
明日的图片: 10 days of Venus and Jupiter
