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| An artist's impression of the possible surface temperatures of Gliese 581d. It orbits a red dwarf star called Gliese 581 (right), located around 20 light years from Earth. Cooler temperatures are represented with blue colours and warmer temperatures red. The arrows represent winds at two-kilometres altitude. |
閱讀難度：
A red dwarf star 20 light-years away is again providing hints that it hosts the first definitively habitable planet outside our Solar System, BBC reports.
The planet Gliese 581d is at the colder outer edge of the "Goldilocks zone" in which liquid water can be sustained.
Now a study in Astrophysical Journal Letters suggests its atmosphere may keep things warm enough for water.
French researchers have run computer simulations of the planet's atmosphere, arguing that it is likely to contain high concentrations of carbon dioxide.
They contend that conditions could be suitable for oceans of liquid water as well as clouds and rainfall. But Gliese 581d's denser air and dim red light from its host star would make for a murky environment that would be toxic to humans.
（點擊英國廣播公司網站查看原文）
科學家發現可居住星球
?????? 據英國廣播公司報道，距離地球20光年的一顆紅色行星顯示它是太陽系外第一顆適合地球生命居住的行星。
?????? 這顆名為葛利斯581d的行星正好位于溫度稍低的“可居住區”內，可以保證液態水的存在。
?????? 《天體物理學快報》上發表的一項研究認為，這里的大氣層可以保溫，因此水才得以存在。
?????? 法國科學家通過電腦模擬該行星上的大氣層發現，大氣層中的二氧化碳含量過高。
?????? 他們認為那里的條件適宜于液態水形成海洋、云和降雨，但由于那里的天空呈混沌、暗紅色，整個昏暗的環境可能對人體有害。
(China.org.cn May 20, 2011) |
