Such stars eventually blow off the material of their outer layers, which creates an expanding shell of gas called a planetary nebula.
这样的恒星最终炸开了它们的外层物质，形成了向外扩展的气体盔甲，名为行星状星云。
Hence, it is rare that an open cluster survives long enough for one of its members to form a planetary nebula.
因此，一个疏散星团很少能够存活到它内部的某个成员变成行星状星云。
The hot core collapses and begins to pulsate, eventually shedding its outer layers of gas to set the stage for the birth of a planetary nebula.
恒星高温的核心坍缩，并开始有规律的振动，最终气体外层迸散，为行星星云的形成提供了有利条件。
That surge could cause the sun to blow even more material into space, adding to its colorful, expanding shell of gas, which astronomers call a planetary nebula.
能量的激增可能会使太阳把更多的物质喷向太空，送入色彩斑斓的、正在膨胀的气体外围之中。天文学家们将这种膨胀的气团称为行星状星云。
The Eskimo nebula is clearly a planetary nebula.
爱斯基摩星云显然是一个行星星云。
See photos of new planetary nebula.
查看新的关于行星云团的照片。
L the Ring nebula in Lyra is the best-known of the planetary nebulae.
l天琴座中的环状星云是最著名的行星状星云。
Also known as Abell 21, this Medusa is an old planetary nebula some 1, 500 light-years away in the constellation Gemini.
也被称作阿贝尔21，水母星云是双子座中一个1500光年远的年老行星状星云。
This particular planetary nebula, pictured above and designated Shapley 1 after the famous astronomer Harlow Shapley, has a very apparent annular ring like structure.
上图中的行星状星云叫做Shapley1以著名天文学家Harlow Shapley的名字命名，它有非常明显的环状结构。
The Cat's Eye nebula (NGC 6543) is one of the best known planetary nebulae in the sky.
猫眼星云(NGC 6453)是天空中最著名的行星状星云之一。
Our own sun will blossom into a planetary nebula when it dies in about five billion years.
大约50亿年后，我们的太阳死去时，也会变成行星状星云。
In tribute to Hubble's longest-running optical camera, a planetary nebula has been imaged as WFPC2's final "pretty picture."
这个行星状星云的照片被看成是WFPC2最后的“漂亮图片”，以向这个哈勃历史最悠久的光学相机表示敬意。
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.
虽然行星状星云阶段持续约1万年，天文学家估计其外晕的丝状物质年龄在5万至9万年间。
Of course, gazing into the Cat's Eye, astronomers may well be seeing the fate of our sun, destined to enter its own planetary nebula phase of evolution ...
当然，天文学家在观察“猫眼”时，就可能也看到了我们的太阳的命运，它最终注定会进入行星星云的演化阶段……
The sands of time are running out for the central star of this hourglass-shaped planetary nebula.
在这一酷似沙漏形状的星云内，“时间之沙”即将从中央星之中流逝殆尽。
The spoke features seem to indicate that the Helix Nebula is itself an old and evolved planetary nebula.
辐射线的特征似乎说明了螺旋状星云本身的古老；历经了行星状星云的演化过程。
But this well-studied example of a planetary nebula, produced near the end of the life of a sun-like star, is now understood to have a surprisingly complex geometry.
但是，这个深入研究的行星状星云的范例，映射着类星体临近死亡的状态；被认为是个令人惊讶极其复杂的几何学。
They needed to show that the molecules are in space, that they have a unique and interesting molecular structure, and that they are associated with a faraway planetary nebula.
他们需要表现出来的几个关键点包括：首先，这种分子是在太空中；其次，它们有独特且有趣的结构；再者，它们和遥远的行星状星云有着密切联系。
The earth developed from a planetary embryo in the solar nebula into the third planet of our solar system.
地球在早期的太阳星云中由行星胎成长为太阳系的第三颗行星。
Since open star clusters disperse after only a few hundred million years, this one must be exceptionally old to have one of its member stars evolve to the planetary nebula stage.
因为在仅仅数百万年之后，疏散星团开始消散，可能因为这个星团异常的年老，其内的一颗恒星已经演变到了行星状星云阶段。
In a few million years, as one of the central stars becomes further depleted of nuclear fuel, the Red Rectangle nebula will likely bloom into a planetary nebula.
在未来的数百万年中，其中心恒星中的一个会耗尽其核反应能源，到时候红矩形星云很可能会变成一个行星状星云。
A planetary nebula is an expanding cloud of gas ejected from a star that is nearing the end of its life.
行星状星云一个由来自中心濒临死亡恒星所释放出的气体组成的正在膨胀的星云。
Shining with light from the central star reflected by dust, the frigid Boomerang Nebula is believed to be a star or stellar system evolving toward the planetary nebula phase.
冰寒的回飞棒星云会发光，是因为它尘埃反射了来自中心星的星光，天文学家认为它是正在演化到行星状星云阶段的恒星或恒星系统。
Shining with light from the central star reflected by dust, the frigid Boomerang Nebula is believed to be a star or stellar system evolving toward the planetary nebula phase.
冰寒的回飞棒星云会发光，是因为它尘埃反射了来自中心星的星光，天文学家认为它是正在演化到行星状星云阶段的恒星或恒星系统。
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