简单的回答是，因为系外行星是根据它们围绕的恒星命名的，小写字母表示被发现的顺序。
The simple answer is that exoplanets are named after the stars they orbit, with lowercase letters tacked on in the order the planets are discovered.
天文学家将这颗行星环绕运行的恒星命名为HIP13044，它距离地球2,000光年，目前已经接近生命的尾声。
The star, called HIP 13044, is nearing the end of its life and is 2000 light years from Earth.
例如，在2007年，HARPS发现了另一个命名为葛利斯581的超级地球，它可能处于宿主恒星的宜居区。
In 2007, for instance, HARPS discovered another super-Earth, called Gliese 581d, that may lie within the habitable zone of its star.
在电影《星球大战》中，虚构的天体塔图因(Tatooine)绕双恒星运行，因此科学家以它来命名此次发现的这颗行星。
They are calling the new planet Tatooine after the fictional body in the "Star Wars" films that boasts a double sunset.
意大利国家天体物理研究所（National Institutefor Astrophysics）（在那不勒斯（in Naples））的罗伯特•斯沃迪（Roberto Silvotti）与其同事发现了这颗像木星般的巨大气化行星。 它所环绕的恒星被命名为V 391Pegasi。
Roberto Silvotti of the National Institute for Astrophysics in Naples and his colleagues spotted the planet, a gaseous giant like Jupiter, circling a star called V 391 Pegasi.
在图像的右上角的亮点是一个名为w3的活跃的恒星形成区域，是由Wright在20世纪70年代在写研究4像素气球传播望远镜的博士论文期间发现并命名的。
The bright spot at the top right of the image is an active star-forming region called W3, which Wright studied with a 4-pixel balloon-borne telescope for his Ph.D. thesis in the 1970s.
由于宇宙中有太多恒星了，所以IAU还使用了另一套不同的系统命名新发现的恒星。
Since there are so many stars in the universe, the IAU USES a different system for newfound stars.
这颗行星被命名为TrES-2b，它仅反射低于1%的恒星光线，这使得它比迄今发现的任何行星或卫星都要暗。
The planet, known as TrES-2b, reflects less than 1 per cent of light, which makes it darker than any other planet or moon.
第一个被发现的太阳系外行星是51PegasiB，它围绕着一颗类日恒星旋转，距离地球约为50光年，它被非正式的命名为Bellerophon，Bellerophon是驯服了文艺女神珀加索斯的一位希腊英雄。
The first discovery of an extrasolar planet around a sun-like star was 51 Pegasi B, an exoplanet roughly 50 light-years away, unofficially named Bellerophon after the tamer of the mythical Pegasus.
这个新的星体被命名为：Kepler 10 - b，它围绕着一个距离560光年类似太阳的恒星运转。
The new planet, called Kepler 10-b, orbits a sun-like star 560 light-years away.
你可以买一颗恒星把它命名为梅丽尔。
红矮星gliese 581没有被正式命名，它出现在德国天文学家威廉·葛利斯(William Gliese)编纂的恒星目录中，参考号为581。
The star has not been given a proper name. It appears in a catalogue of stars compiled by the German astronomer William Gliese where it has been given the reference number 581.
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。
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。
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.
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