VOA常速英语2008年-Star's Dust Shows Signs of Possible Planet Form

By Mona Ghuneim
New York
27 March 2008

Astronomers¹ have captured an image that suggests evidence of a planet in the early stages of formation.  From VOA's New York Bureau, Mona Ghuneim reports on this discovery that has opened a new window onto our endless search for understanding of that final frontier.

Scientists are one step closer to understanding how new planets evolve.  A recent image of gas and dust circling a star in the constellation² Auriga shows material that may be forming into a planet. 

A group of astrophysicists, led by Ben Oppenheimer at the American Museum of Natural History in New York, has detected a gap in the disk surrounding a well-studied star called AB Aurigae. 

According to the scientists, it appears that an object between five and 37 times the mass of the planet Jupiter is forming around this star.  AB Aurigae is one to 3 million years of age and around 470 light years away, considered in astronomy to be both young and nearby in relation to the Earth.   

While Oppenheimer cannot confirm yet that this is a planet in the making, he says this discovery is in line with scientific theory on planet formation. 

"The structure that we've imaged here seems to indicate or at least is very similar to theories of what happens to dust in these disks when a planet actually is forming," he said.  "The planet will perturb³ the distribution of this dust and make it accumulate in certain areas which we seem to be seeing and also for the disk to have deficits⁴ in certain areas which we also observed."

Whatever it is, says Oppenheimer, it is an intriguing⁵ observation and can shed more light on the field of exoplanetary science, the study of planets orbiting stars other than the sun.

Oppenheimer says he and his group used a coronagraph developed by the museum to basically filter out the extreme light of the star in order to view the stellar disk.  The device was attached to a US Air Force telescope on the island of Maui in the state of Hawaii.

Sasha Hinkley is a Columbia University graduate student in astrophysics and one of the scientists on Oppenheimer's team.  He says that the result is a big step in an attempt to directly photograph existing and forming planets, but that there is still a lot of work to be done.  He is urging caution about calling the discovery a planet as this is an early observation of a solar system. 

"We do need to be careful.  This is an extremely challenging task, because we're really at the forefront of detecting something extremely faint around a star," he explained.  "We're talking about something that's roughly 100,000 times fainter than the star so we're really at the threshold of what is possible for human beings to do."

Julian Christou is an astrophysicist and program officer at the National Science Foundation, a government agency that partially⁶ funded this project.

Christou says that up until the past ten years, there was no evidence to suggest that we were not the only solar system.  But in that time, scientists developed an indirect technique, called spectroscopy, which showed proof of other planets.  These 150 or so planets that have been discovered, he says, have not been seen, but rather detected by the effect of their motion around other stars. 

Christou says this new discovery by the team made up of museum, university, independent and government scientists could help answer some big questions.

"Here for the first time we actually see what happens in an early solar system, how our solar system may have looked, by analogy, three billion/four billion years ago, how did the planets surrounding our sun form, and of course one of those planets is the Earth," he said.  "So how did the Earth form? Where did it come out of?"

The scientists say more aggressive study and advanced technology will follow.  Oppenheimer admits that the ultimate goal of this sort of research is to find an object like Earth and then look for signs of biological activity on it.

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 constellation   

n.星座n.灿烂的一群

参考例句：

• A constellation is a pattern of stars as seen from the earth. 一个星座只是从地球上看到的某些恒星的一种样子。
• The Big Dipper is not by itself a constellation. 北斗七星本身不是一个星座。

3 perturb   

v.使不安，烦扰，扰乱，使紊乱

参考例句：

• Stellar passings can perturb the orbits of comets.行星的运行会使彗星的轨道发生扰动。
• They perturb good social order with their lie and propaganda.他们以谎言和宣传扰乱良好的社会秩序。

4 deficits   

n.不足额( deficit的名词复数 )；赤字；亏空；亏损

参考例句：

• The Ministry of Finance consistently overestimated its budget deficits. 财政部一贯高估预算赤字。 来自《简明英汉词典》
• Many of the world's farmers are also incurring economic deficits. 世界上许多农民还在遭受经济上的亏损。 来自辞典例句

5 intriguing   

adj.有趣的；迷人的v.搞阴谋诡计(intrigue的现在分词)；激起…的好奇心

参考例句：

• These discoveries raise intriguing questions. 这些发现带来了非常有趣的问题。
• It all sounds very intriguing. 这些听起来都很有趣。 来自《简明英汉词典》

6 partially   

adv.部分地，从某些方面讲

参考例句：

• The door was partially concealed by the drapes.门有一部分被门帘遮住了。
• The police managed to restore calm and the curfew was partially lifted.警方设法恢复了平静，宵禁部分解除。