太阳系外40光年处发现的“超级地球”有望孕育生命

在过去20年里，数以千计的系外行星被发现，但绝大多数不符合“超级地球”的条件：不是太热就是太冷，或无法拥有像地球一样的自然环境。而最新发现的这颗“超级地球”位于主星的“宜居带”且很可能拥有液态水，是在太阳系外寻找生命迹象的最佳选择。

Point a high-powered telescope at the constellation Cetus, the sea monster, and it is just possible to make out a dim red dwarf star shining in the tail.
使用高倍率望远镜观察鲸鱼座（Ceuts，名为海怪），也只能勉强看到星座尾部有一颗昏暗的红矮星在发光。

Although it might seem unspectacular, orbiting around that star is a rocky planet that could hold the answer to whether we are alone in the universe.
虽然可能看起来不显眼，但这颗红矮星周围有一颗岩石行星绕其转动，这颗行星也许可以回答宇宙中是否还有其他生命存在这一问题。

Scientists say the planet is a ‘Super-Earth’ which is the best place to look for signs of life outside of the Solar System.
科学家表示，这颗行星是一个“超级地球”，是在太阳系外寻找生命迹象的最佳选择。

Early indications suggest it has an atmosphere, and sits within the ‘Goldilocks Zone’ where it is neither too hot nor too cold for liquid water to exist.
早期迹象表明，该行星拥有大气层，并且位于“可居住带”内，既不会太热，也不会太冷，适合液态水存在。

And it is only 40 light years from Earth meaning that it could be possible to send a signal.
而且它距离地球只有40光年的距离，这意味着发送信号是存在可能性的。

“This is the most exciting exoplanet I’ve seen in the past decade,” said lead author Jason Dittmann of the Harvard-Smithsonian Center for Astrophysics.
来自哈佛-史密森天体物理中心的主要作者杰森•迪特曼说：“这是过去十年中我看到的最令人振奋的外部行星。”

“We could hardly hope for a better target to perform one of the biggest quests in science -- searching for evidence of life beyond Earth.”
“在进行寻找地球以外的生命迹象这一科学领域最伟大的任务时，我们很难再找到比这颗行星更适合的目标了。”

The planet was found by an international team of scientists who have been studying data from European Space Observatory’s High Accuracy Radial velocity Planet Searcher (HARPS) instrument which looks for regular changes in brightness of stars, which suggests a planet is passing by in orbit.
一个国际科学家团队发现了这颗行星，他们一直通过从欧洲空间天文台高精度径向速度行星探测器（HARPS）得到的数据进行研究。该仪器负责探测表明行星经过轨道的恒星亮度变化。

The new world - dubbed LHS 1140b - is ten times closer to its parent star than Earth but because a red dwarf is far cooler than our own yellow dwarf, the planet still sits in the habitable zone.
这一新发现的行星被称为LHS 1140b，与其母星的距离是地球与太阳距离的十分之一，但由于红矮星比身为黄矮星的地球要冷得多，所以该行星还是位于宜居带。

“The present conditions of the red dwarf are particularly favourable -- LHS 1140b spins more slowly and emits less high-energy radiation than other similar low-mass stars,” added team member Nicola Astudillo-Defru from Geneva Observatory, Switzerland.
瑞士日内瓦天文台的团队成员尼科拉•阿斯图迪略•德弗吕补充说道：“这颗红矮星目前的状况非常有利，LHS 1140b的转速比其他类似的低质量恒星更慢，高能辐射更低。”

For life as we know it to exist, a planet must have liquid surface water and retain an atmosphere.
我们所了解的生命能够存在的条件是，行星必须有液态地表水，并且拥有大气。

In this case, the planet’s large size and closeness to its sun means that a magma ocean could have existed on its surface for millions of years, which fed steam into the atmosphere, replenishing the planet with water.
对于这颗行星来说，体积大并且与母星距离近意味着其表面可能有存在了数百万年的岩浆海洋。海洋能够释放蒸汽到大气中，为整颗行星补充水分。

Astronomers estimate the age of the planet to be at least five billion years, just a little older than Earth. They also deduced that it has a diameter 1.4 times larger than the Earth.
天文学家估计，这颗行星的年龄至少为50亿年，比地球存在的时间只长一点。他们还推测其直径是地球直径的1.4倍。

But with a mass around seven times greater than the Earth, and hence a much higher density, it implies that the exoplanet is probably made of rock with a dense iron core.
但是它的质量大约是地球的7倍，所以密度要比地球高得多，这意味着这颗外部行星很有可能是由内核为高密度铁的岩石组成。