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。
Planetary nebulae fade away gradually over tens of thousands of years.
行星状星云在数万年间逐渐衰老。
Stars that form planetary nebulae typically live for billions of years.
具有代表性的是，构成行星状星云的恒星已经存活了十亿年。
Planetary nebulae are not as airy and tranquil as their images suggest.
星云并不如影像中所显现的那么飘逸宁静。
This fraction matches the fraction of planetary nebulae that are bipolar.
这个比例符合双极星云在行星状星云中所占的比例。
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。
NGC 2818 is one of very few planetary nebulae in our galaxy located within an open cluster.
NGC2818是银河系中少数几个位于疏散星团内部的行星状星云之一。
Glowing in vibrant colors, planetary nebulae, such as this one, represent the death rattles of dying stars.
在跳跃的颜色中烁烁发光的行星状星云(就像上面这颗)向人们描绘出垂死恒星的最后色彩。
Tne binary interactions play an important role in the formation and shaping of planetary nebulae (PNe).
在行星状星云形成过程中双星起着非常重要的作用。
Planetary nebulae are a type of isolated gaseous nebulae possessing a fair degree of bilateral symmetry.
行星状星云是一类孤立的气体星云，具有相当程度的双侧对称性。
We find a total of 100 emission-line objects, of which 96 are galaxies, the rest being 3 planetary nebulae and 1 star.
文中的表1包括100个发射线天体，其中的96个是发射线星系；其余的对象有3个行星状星云，1个发射线星。
In 1995, astronomers used the Hubble Space Telescope to make a series of images of planetary nebulae, including the one above.
在1995年，天文学家用哈勃太空望远镜捕捉到一系列的行星状星云图像，其中包括上面这幅图像。
Astronomers used the Hubble Space Telescope to make a series of images of planetary nebulae in the mid-1990s, including this one.
上世纪九十年代中期，天文学家们运用哈勃太空望远镜拍摄到了这一星云的众多图像，其中便包括了这一张。
How planetary nebulae can form such complex structures, however, is a hot debate among professional astronomers such as Jacoby.
然而，关于行星星云如何形成这么复杂的结构，却在Jacoby等专业天文学家中引发了一场热烈的争论。
Captured in colorful telescopic portraits, two cosmic owls glare back toward planet Earth in this intriguing comparison of planetary nebulae.
这两张望远镜彩色照片拍到了两个宇宙级夜枭，两个行星状星云向行星地球反射强光形成了有趣的对比。
Although he did not know it at the time, this was the first in a class of objects, now known as planetary nebulae, to make it into the catalog.
尽管他当时并不知道，这是首个被记录在册的行星状星云。
Planetary nebulae, historically named for their resemblance to gas-giant planets, are now known to be the remains of stars that once looked a lot like our sun.
行星状星云，在历史上曾因他们像巨型气态行星而被命名，目前已知的是它很像我们太阳的恒星遗骸。
The intriguing result implies that the massive star's explosion has produced a shape similar to what is seen in some planetary nebulae associated with lower mass stars.
这个很有趣的结果指出，大质量恒星爆炸所产生的碎片云，其外观和某些小质量恒星所产生的行星状星云相似。
Planetary nebulae are produced during a final phase in the life of a sun-like star, an example of the fate that awaits the sun when it runs out of nuclear fuel in another 5 billion years.
行星状星云是类太阳恒星在其生命最后阶段形成的，50亿年后太阳核燃料耗尽时也将面临这样的命运。
Kronberger 61 lies roughly 13, 000 light-years away in the Cygnus constellation and is almost perfectly round-an oddity when compared with the other 3, 000 or so planetary nebulae already discovered.
Kronberger 61距离地球大约13,000光年，是天鹅座的一名“成员”。它几近完美的球形；相较于其他3,000余行星星云，它可谓十分不同寻常。
Kronberger 61 lies roughly 13, 000 light-years away in the Cygnus constellation and is almost perfectly round-an oddity when compared with the other 3, 000 or so planetary nebulae already discovered.
Kronberger 61距离地球大约13,000光年，是天鹅座的一名“成员”。它几近完美的球形；相较于其他3,000余行星星云，它可谓十分不同寻常。
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