VOA科学技术2024--Study: New Evidence Suggests Earth-like Exoplanet May Hold Liquid Ocean

Researchers say new telescope observations suggest an Earth-like planet outside our solar system may hold a large liquid ocean.

The exoplanet is known as LHS 1140 b. Astronomers¹ believe it sits about 48 light years away from Earth. A light year is the distance light travels in a year - about 9.5 trillion kilometers.

The research - led by astronomers at the University of Montreal in Canada - shows the possibility the exoplanet might hold the right conditions to support some form of life. A study explaining the findings recently appeared in The Astrophysical Journal Letters.

The study is based on observations collected in December 2023 by the James Webb Space Telescope. The American space agency NASA operates the orbiting observatory².

Researchers combined the information from the James Webb with existing data to make new estimates for the exoplanet's mass and size. These suggest that LHS 1140 b is "a promising³ super-Earth ice or water world," the University of Montreal said in a statement.

Some past studies had suggested the exoplanet might be a gas giant, also known as a mini-Neptune. But the researchers said the new study provides evidence that LHS 1140 b is more likely a super-Earth, a rocky planet bigger than Earth.

The new research supports a NASA-led study from October 2023 that suggested at least 17 observed exoplanets could hold oceans of liquid water. That study noted⁴ that sometimes water from these oceans likely breaks through large pieces of ice to form geysers.

Scientists had already identified LHS 1140 b as being within its star's "habitable zone." Exoplanets found within this zone are believed to have temperatures that would permit water to exist in liquid form.

Measurements made by the James Webb data suggest the exoplanet "is less dense⁵" than expected for a rocky, Earth-like body. The researchers estimated that 10 to 20 percent of LHS 1140 b's mass might be made up of water. The possibility of a large liquid ocean would be found on the side of the planet always facing the star that it orbits.

The new data collected by the James Webb showed the exoplanet might also have a nitrogen-rich atmosphere. This differs from earlier research that suggested a possible atmosphere that was mostly hydrogen.

Charles Cadieux is a doctoral student at the University of Montreal's Trottier Institute for Research on Exoplanets. He was the lead writer of the study.

Cadieux said in a statement, "Of all currently known temperate⁶ exoplanets, LHS 1140 b could well be our best bet to one day indirectly⁷ confirm liquid water on the surface of an alien world beyond our solar system." He noted that if the study's findings can be confirmed, the data would represent "a major milestone⁸" in the search for exoplanets that could possibly support life.

René Doyon is a project scientist at the University of Montreal. He helped lead the research. He said more observations will be needed to confirm the current study's findings. "The current hint of a nitrogen-rich atmosphere begs for confirmation⁹ with more data," Doyon said.

He estimated that at least one more year of observations will be needed "to confirm that LHS 1140 b has an atmosphere."

The process of confirming whether carbon dioxide is present in the atmosphere and liquid water exists on the surface would likely require several years of observations, Doyon noted.

Ryan MacDonald is a NASA Sagan Fellow in the University of Michigan's Department of Astronomy who helped examine the James Webb data. He said, "This is the first time we have ever seen a hint of an atmosphere on a habitable zone rocky or ice-rich exoplanet."

With further data collection and investigation¹⁰, MacDonald noted there is a good possibility "we might just have found evidence of air on this world."

Words in This Story

geyser - n. a hole in the ground from which hot water and steam come out

habitable - adj. able to support life

best bet - idiom. the action that is most likely to be successful

alien - n. relating to creatures from another planet

milestone - n. an important event in the development or history of something

hint - n. to suggest or indicate something in an indirect way

beg - v. to make a very strong and urgent request

1 astronomers   

n.天文学者，天文学家( astronomer的名词复数 )

参考例句：

• Astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
• Astronomers used to ask why only Saturn has rings. 天文学家们过去一直感到奇怪，为什么只有土星有光环。 来自《简明英汉词典》

2 observatory   

n.天文台，气象台，瞭望台，观测台

参考例句：

• Guy's house was close to the observatory.盖伊的房子离天文台很近。
• Officials from Greenwich Observatory have the clock checked twice a day.格林威治天文台的职员们每天对大钟检查两次。

3 promising   

adj.有希望的，有前途的

参考例句：

• The results of the experiments are very promising.实验的结果充满了希望。
• We're trying to bring along one or two promising young swimmers.我们正设法培养出一两名有前途的年轻游泳选手。

4 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

5 dense   

a.密集的，稠密的，浓密的；密度大的

参考例句：

• The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
• The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。

6 temperate   

adj.温和的，温带的，自我克制的，不过分的

参考例句：

• Asia extends across the frigid,temperate and tropical zones.亚洲地跨寒、温、热三带。
• Great Britain has a temperate climate.英国气候温和。

7 indirectly   

adv.间接地，不直接了当地

参考例句：

• I heard the news indirectly.这消息我是间接听来的。
• They were approached indirectly through an intermediary.通过一位中间人，他们进行了间接接触。

8 milestone   

n.里程碑；划时代的事件

参考例句：

• The film proved to be a milestone in the history of cinema.事实证明这部影片是电影史上的一个里程碑。
• I think this is a very important milestone in the relations between our two countries.我认为这是我们两国关系中一个十分重要的里程碑。

9 confirmation   

n.证实，确认，批准

参考例句：

• We are waiting for confirmation of the news.我们正在等待证实那个消息。
• We need confirmation in writing before we can send your order out.给你们发送订购的货物之前，我们需要书面确认。

10 investigation   

n.调查，调查研究

参考例句：

• In an investigation,a new fact became known, which told against him.在调查中新发现了一件对他不利的事实。
• He drew the conclusion by building on his own investigation.他根据自己的调查研究作出结论。