太陽系外40光年處發(fā)現(xiàn)的“超級地球”有望孕育生命

在過去20年里，數(shù)以千計的系外行星被發(fā)現(xiàn)，但絕大多數(shù)不符合“超級地球”的條件：不是太熱就是太冷，或無法擁有像地球一樣的自然環(huán)境。而最新發(fā)現(xiàn)的這顆“超級地球”位于主星的“宜居帶”且很可能擁有液態(tài)水，是在太陽系外尋找生命跡象的最佳選擇。

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.

使用高倍率望遠鏡觀察鯨魚座(Ceuts，名為海怪)，也只能勉強看到星座尾部有一顆昏暗的紅矮星在發(fā)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.

雖然可能看起來不顯眼，但這顆紅矮星周圍有一顆巖石行星繞其轉(zhuǎn)動，這顆行星也許可以回答宇宙中是否還有其他生命存在這一問題。

Scientists say the planet is a ‘Super-Earth’ which is the best place to look for signs of life outside of the Solar System.

科學家表示，這顆行星是一個“超級地球”，是在太陽系外尋找生命跡象的最佳選擇。

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.

早期跡象表明，該行星擁有大氣層，并且位于“可居住帶”內(nèi)，既不會太熱，也不會太冷，適合液態(tài)水存在。

And it is only 40 light years from Earth meaning that it could be possible to send a signal.

而且它距離地球只有40光年的距離，這意味著發(fā)送信號是存在可能性的。

“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.

來自哈佛-史密森天體物理中心的主要作者杰森•迪特曼說：“這是過去十年中我看到的最令人振奮的外部行星。”

“We could hardly hope for a better target to perform one of the biggest quests in science -- searching for evidence of life beyond Earth.”

“在進行尋找地球以外的生命跡象這一科學領(lǐng)域最偉大的任務(wù)時，我們很難再找到比這顆行星更適合的目標了。”

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.

一個國際科學家團隊發(fā)現(xiàn)了這顆行星，他們一直通過從歐洲空間天文臺高精度徑向速度行星探測器(HARPS)得到的數(shù)據(jù)進行研究。該儀器負責探測表明行星經(jīng)過軌道的恒星亮度變化。

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.

這一新發(fā)現(xiàn)的行星被稱為LHS 1140b，與其母星的距離是地球與太陽距離的十分之一，但由于紅矮星比身為黃矮星太陽要冷得多，所以該行星還是位于宜居帶。

“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.

瑞士日內(nèi)瓦天文臺的團隊成員尼科拉•阿斯圖迪略•德弗呂補充說道：“這顆紅矮星目前的狀況非常有利，LHS 1140b的轉(zhuǎn)速比其他類似的低質(zhì)量恒星更慢，高能輻射更低。”

For life as we know it to exist, a planet must have liquid surface water and retain an atmosphere.

我們所了解的生命能夠存在的條件是，行星必須有液態(tài)地表水，并且擁有大氣。

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.

對于這顆行星來說，體積大并且與母星距離近意味著其表面可能有存在了數(shù)百萬年的巖漿海洋。海洋能夠釋放蒸汽到大氣中，為整顆行星補充水分。

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.

天文學家估計，這顆行星的年齡至少為50億年，比地球存在的時間只長一點。他們還推測其直徑是地球直徑的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.

但是它的質(zhì)量大約是地球的7倍，所以密度要比地球高得多，這意味著這顆外部行星很有可能是由內(nèi)核為高密度鐵的巖石組成。