猫眼又宽又深
(原标题: Cat's Eye Wide and Deep)
2023-05-25
浏览次数: 13
猫眼星云（NGC 6543）是天空中最著名的行星状星云之一。在这张令人印象深刻的广角照片中，我们可以在星云较亮的中心区域看到它更熟悉的轮廓。但这张结合了两个望远镜数据的宽而深的图像也揭示了它极其微弱的外晕。在大约3000光年的距离上，暗淡的外晕直径超过5光年。长期以来，行星状星云一直被认为是类太阳恒星生命的最后阶段。最近，一些行星状星云被发现有像这样的光晕，可能是由恒星早期演化过程中脱落的物质形成的。虽然行星状星云阶段被认为持续了大约1万年，但天文学家估计这个光晕的外部丝状部分的年龄在5万到9万年之间。在右边可以看到，距离行星状星云大约5000万光年的地方，是螺旋星系NGC 6552。
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The Cat's Eye Nebula (NGC 6543) is one of the best known planetary nebulae in the sky. Its more familiar outlines are seen in the brighter central region of the nebula in this impressive wide-angle view. But this wide and deep image combining data from two telescopes also reveals its extremely faint outer halo. At an estimated distance of 3,000 light-years, the faint outer halo is over 5 light-years across. Planetary nebulae have long been appreciated as a final phase in the life of a sun-like star. More recently, some planetary nebulae are found to have halos like this one, likely formed of material shrugged off during earlier episodes in the star's evolution. While the planetary nebula phase is thought to last for around 10,000 years, astronomers estimate the age of the outer filamentary portions of this halo to be 50,000 to 90,000 years. Visible on the right, some 50 million light-years beyond the watchful planetary nebula, lies spiral galaxy NGC 6552.
© Jean-François Bax