科學家發(fā)現地球“雙胞胎”

Chance discovery uncovers mysterious planet 200 light years away with the same mass as our world

中國日報網 2014-01-08 16:39

Earth's gassy twin as been discovered in another solar system 200 light years away. Pictured is an artist's impression of KOI-314c in orbit around its star. It orbits a dim red dwarf star at such a close distance that temperatures on its surface could be as high as 104°C

點擊進入iNews

Scientists believe one in five stars in our galaxy have Earth-like planets orbiting them.

But the ultimate goal of finding a world that truly resembles our own has continued to elude astronomers.

Now researchers have come a step closer by finding Earth's gassy twin in another solar system 200 light years away.

It orbits a dim red dwarf star at such a close distance that temperatures on its surface could be as high as 104°C - too hot for most forms of life on Earth.

KOI-314C is only 30 per cent more dense than water. This suggests that the world is enveloped by a blanket of hydrogen and helium hundreds of miles thick.

Scientists believe it may have started life as a mini-Neptune before some of its atmospheric gases were blasted away by intense radiation from the parent star.

'This planet might have the same mass as Earth, but it is certainly not Earth-like,' said lead astronomer Dr David Kipping from the Harvard-Smithsonian Centre for Astrophysics.

'It proves that there is no clear dividing line between rocky worlds like Earth and fluffier planets like water worlds or gas giants.'

The findings were presented at the annual meeting of the American Astronomical Society in Washington DC.

To weigh KOI-314c, the scientists used a new technique called transit timing variations (TTV), which only works when more than one planet orbits a star.

The two planets tug on each other, slightly altering the time they take to cross or 'transit' the star's face.

Analysing the way the planetary wobbles affect light coming from the star makes it possible to calculate their mass.

KOI-314c's companion world is similar to it in size but weighs four times more than the Earth.

The new discovery was made by chance as scientists scoured data from the Kepler space telescope looking for evidence of moons rather than planets.

'When we noticed this planet showed transit timing variations, the signature was clearly due to the other planet in the system and not a moon,' said Dr Kipping.

'At first we were disappointed it wasn't a moon, but then we soon realised it was an extraordinary measurement.'

據英國《每日郵報》報道，科學家發(fā)現在距離地球200光年的地方有一顆與地球質量相同的神秘行星。

盡管科學家認為在銀河系中五分之一的恒星都有一個與地球相似的行星圍繞其運行，但是天文學家們卻從未找到另外一個與地球真正相似的世界。

不過，研究者們最近離這一目標又近了一步，在距離地球200光年的外星系中發(fā)現了地球的“雙胞胎”。

這顆被稱為“KOI-314c”的行星，質量與地球相當，但是體積比地球大60%。科學家懷疑這是因為它的大氣層更厚。

這顆行星圍繞一顆暗紅色的小行星近距離運行，因此其表面溫度高達104攝氏度，這個溫度對于地球上的大部分生物來說都太高。

行星”KOI-314C“的密度只比水高30%。這意味著它被厚達幾百英里的氫氣和氦氣像毯子一樣包裹著。但是科學家認為，在其大氣受到來自恒星的強輻射而爆炸之前，這顆行星可能已經像一顆迷你海王星那樣運行。

哈佛大學史密森尼天體物理學中心的David Kipping博士則認為：“這顆行星可能只是與地球質量相同，但肯定不是與地球相似的行星。”

此前，科學家試圖從開普勒太空望遠鏡的數據中尋找與地球相似的衛(wèi)星，而這顆行星是機緣巧合下的新發(fā)現。

相關閱讀

（莫競西編輯：信蓮）

上一篇 : 丹麥人為找工作不惜將自己放在櫥窗展示
下一篇 : 極端嚴寒天氣席卷美國芝加哥變身“芝伯利亞”

中國日報網英語點津版權說明：凡注明來源為“中國日報網英語點津：XXX（署名）”的原創(chuàng)作品，除與中國日報網簽署英語點津內容授權協(xié)議的網站外，其他任何網站或單位未經允許不得非法盜鏈、轉載和使用，違者必究。如需使用，請與010-84883561聯(lián)系；凡本網注明“來源：XXX（非英語點津）”的作品，均轉載自其它媒體，目的在于傳播更多信息，其他媒體如需轉載，請與稿件來源方聯(lián)系，如產生任何問題與本網無關；本網所發(fā)布的歌曲、電影片段，版權歸原作者所有，僅供學習與研究，如果侵權，請?zhí)峁┌鏅嘧C明，以便盡快刪除。