- rzp wrote:
这张像在哪见过。劳烦哪位解释一下，这张相里哪些部分分别是：“慧星的尘埃”，“距地球700光年的星云”、“类似地球的星体”。谢谢。
July wrote:
第四：旋涡星云
美国宇航局2月12日公布的斯皮策太空望远镜拍摄的图片显示，来自慧星的尘埃将遥远的“旋涡星云”之“眼”包围起来。距地球700光年的星云是一颗接近死亡的类似地球的残留物。类似地球的星体正释放出外层物质以成为一颗白矮星。
古狗了一下。
我的理解，这个物体名叫 The Helix Nebula，螺旋状行星尘，编号 NGC 7293。可以把它想像为一个弹簧，你从弹簧的一端看进去就是这个样子。它离地球很近，用业余天文望远镜可以观察。图像中央是一颗白矮星，也就是濒死的恒星，预示了我们的太阳的将来。那时候太阳系的包括地球在内的行星们也会像这样“零落成泥碾作尘”，被膨胀的太阳包裹，烧成灰烬，但这些灰烬仍然围绕着太阳，在已经冷却的太阳余热照射下发出荧光。
Credit: NASA, WIYN, NOAO, ESA, Hubble Helix Nebula Team, M. Meixner (STScI), & T. A. Rector (NRAO)
Explanation: Will our Sun look like this one day? The Helix Nebula is the closest example of a planetary nebula created at the end of the life of a Sun-like star. The outer gasses of the star expelled into space appear from our vantage point as if we are looking down a helix. The remnant central stellar core, destined to become a white dwarf star, glows in light so energetic it causes the previously expelled gas to fluoresce. The Helix Nebula, given a technical designation of NGC 7293, lies about 650 light-years away towards the constellation of Aquarius and spans about 2.5 light-years. The above picture is a composite of newly released images from the ACS instrument on the Hubble Space Telescope and wide-angle images from the Mosaic Camera on the WIYN 0.9-m Telescope at Kitt Peak National Observatory. A close-up of the inner edge of the Helix Nebula shows complex gas knots of unknown origin.
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