The interaction of two doomed stars has created this spectacular ring adorned with bright clumps of gas ­– a diamond necklace of cosmic proportions. Fittingly known as the “Necklace Nebula,” this planetary nebula is located 15,000 light-years away from Earth in the small, dim constellation of Sagitta (the Arrow).

A pair of tightly orbiting Sun-like stars produced the Necklace Nebula, which also goes by the less glamorous name of PN G054.203.4. Roughly 10,000 years ago, one of the aging stars expanded and engulfed its smaller companion, creating something astronomers call a “common envelope.” The smaller star continued to orbit inside its larger companion, increasing the bloated giant’s rotation rate until large parts of it spun outwards into space. This escaping ring of debris formed the Necklace Nebula, with particularly dense clumps of gas forming the bright “diamonds” around the ring.

The pair of stars which created the Necklace Nebula remain so close together – separated by only several million miles – that they appear as a single bright dot in the center of this image. Despite their close encounter, the stars are still furiously whirling around each other, completing an orbit in just over a day.

Hubble previously released an image of the Necklace Nebula, but this new image uses advanced processing techniques to create an improved and fresh view of this intriguing object. The composite image includes several exposures from Hubble’s Wide Field Camera 3.

Text credit: European Space Agency (ESA)
Image credit: ESA/Hubble & NASA, K. Noll


一对紧绕太阳运行的恒星形成了项链星云,它还有一个不那么迷人的名字PN G054.203.4。大约1万年前,其中一颗老化的恒星膨胀并吞噬了它较小的同伴,创造了天文学家所说的“公共包层”。这颗小恒星继续在那颗大恒星的内部运行,增加了这颗膨胀的巨星的自转速度,直到它的大部分向外旋转进入太空。这一逃逸的碎片环形成了项链星云,特别密集的气体团形成了环周围明亮的“钻石”。



图片来源:ESA/Hubble & NASA, K. Noll

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