Cat’s Eye Wide and Deep
Image Credit & Copyright: Jean-François Bax, Guillaume Gruntz
Explanation: 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.
Tomorrow’s picture: Virgo Cluster Galaxies
猫眼星云的大视野深场影像
影像提供与版权: Jean-François Bax, Guillaume Gruntz
说明: 猫眼星云（NGC 6543）是天空最著名的行星状星云之一。在这张精采的广角影像里，我们较熟悉的形貌是这团星云较明亮的中心区。然而，这幅组合自2部望远镜拍摄的多张短和长曝光照片的影像，也呈现了极为昏暗的外晕。以此星云3,000光年的估计距离来推算，这个昏暗外晕的宽度在5光年以上。虽然长久以来，行星状星云咸认是类太阳恒星生命的最后一章，不过发现部分行星状星云具有外晕，则是晚近的事。而这种外晕，很可能是恒星在演化较早期所抛出的物质。虽然行星状星云阶段存续的时间大约在1万年左右，不过天文学家估计上面这个外晕的丝缕状构造，年龄介于50,000年到90,000年之间。在影像的左侧，还可见到位在这团星云后方大约5千万光年处的螺旋星系NGC 6552。
明日的图片: Virgo Cluster Galaxies
