找到你了！科学家发现现实版“三体星系”
由博士一年级在读学生所发现的HD 131399的图像。（图像来源：视觉中国）
中国日报网7月8日电（沈洋）在科幻小说《三体》中，中国作家刘慈欣以其丰富的想象力虚构了一个复杂的三体星系，并由此引出了地球文明在宇宙中的兴衰史，让广大科幻迷们过足了瘾。据澳大利亚广播公司新闻网站报道，一个由天文学家组成的国际团队日前发布声明说他们发现了一个与太阳系相距遥远的奇怪行星，这颗行星就拥有3个“太阳”。
拥有两颗恒星的星系在宇宙中可能相对普遍，但专家表示包含3个或以上恒星的恒星系统还是比较罕见的。
该研究团队在美国《科学》杂志刊发的研究文章显示，这颗被命名为HD 131399Ab的遥远的行星绕着三颗恒星中最亮的一颗公转，公转轨道周期长达1100年。
HD 131399Ab 的发现者、文章的第一作者凯文 魏格纳还是一位博士一年级在读生。他解释到：“在这颗行星公转轨道周期的大约一半时间（约550个地球年）中，三颗恒星在其天空上都是可见的。其中较为暗淡的两颗总是距离非常近，并且和最大的那颗明显分离。”
凯文·万格还补充说，“在这颗行星公转轨道周期的大部分时间中，系统内的三颗恒星都距离很近，使得这个星球上出现了我们所熟悉的昼夜交替，不过这颗行星在一天之中会分别经历三次日出日落。随着行星的运行，3颗恒星彼此日益远离，在一个时刻又会到达某一点——一颗恒星落下恰好伴随着另一颗升起。”这样造成的结果就是“在这颗行星公转轨道周期约四分之一的时间（约140个地球年）里，这颗行星上几乎一直都是白昼。”
领导此研究团队的亚利桑那大学科学家表示：“想象一下在一个星球上，根据季节的变化，要么就是一直在经历白天，要么就是每天都要迎接三次日出日落，而一个季节持续的时间要比人类个体的一生还要长。”
此次被发现的HD 131399Ab是该天文团队利用位于智利的欧洲南方天文台“甚大望远镜”发现的。这颗行星位于人马座中，距离地球340光年，质量是我们太阳系中质量最大的行星——木星的4倍。科学家们认为它相对较为年轻，形成于距今约1600万年前，是迄今为止人类所发现的太阳系系外行星中最年轻的一个。
（编辑：刘世东）
HD 131399Ab: Scientists discover strange planet with three suns
An international team of astronomers have announced the discovery of a strange planet in a faraway solar system that contains not just one sun, but three.
The distant planet, named HD 131399Ab, appears even more unusual than the home planet of Luke Skywalker in the Star Wars saga, Tatooine, which orbited around two suns, according to the findings published in the US journal Science.
Such binary solar systems may be relatively common in the universe, but experts said those involving three stars or more were rare.
"Imagine this: a planet where you'd either experience constant daylight or enjoy triple sunrises and sunsets each day, depending on the seasons, which happen to last longer than human lifetimes," a statement from the University of Arizona, which led the astronomy team, read.
The planet is located about 340 light years from Earth in the constellation Centaurus.
The cosmic body is believed to be relatively young, about 16 million years old, which makes it one of the youngest planets discovered outside our solar system to date.
Its mass is believed to be four times that of the gas giant Jupiter — our solar system's largest planet.
It orbits the brightest of the three stars on a very long and wide path.
"For about half of the planet's orbit, which lasts 550 Earth-years, three stars are visible in the sky — the fainter two always much closer together and changing in apparent separation from the brightest star throughout the year," first author Kevin Wagner, a first-year PhD student who discovered HD 131399Ab, said.
"For much of the planet's year, the stars appear close together, giving it a familiar night-side and day-side with a unique triple-sunset and sunrise each day," Mr Wagner added.
"As the planet orbits and the stars grow further apart each day, they reach a point where the setting of one coincides with the rising of the other."
The result is "near-constant daytime for about one-quarter of its orbit, or roughly 140 Earth-years".
The astronomy team spotted the planet using the SPHERE instrument on the European Southern Observatory's (ESO) Very Large Telescope in Chile.
