VOA标准英语2010年-Astronomers Listen to Stars' 'Giant Co

For thousands of years, humans have gazed up at the night sky and watched the stars. Now, NASA's Kepler mission gives scientists the chance to listen to the stars.? Astronomers¹ are using stellar soundwaves to measure stars more accurately² than ever before.

It might not sound like much.

... but you just heard a star. Actually, a few vibrating red giant stars.

"A Kepler red giant concert, so to say," said Daniel Huber.

Daniel Huber is a doctoral student at the University of Sydney in Australia. He is a member of an international team of astronomers that is using data from NASA's Kepler spacecraft to study stars and their structures.

Kepler uses a huge digital camera to continuously monitor the brightness of more than 150,000 stars as it orbits the sun.
Huber is among the scientists who study red giant stars, which are nearing the ends of their lives.

Scientists say the stars get older, temperatures near their cores rise and their sizes expand.

"Every red giant that we've detected oscillations in has its unique sound, its unique amplitude³ and frequency, and we can therefore say that Kepler is basically listening to thousands of "musicians" in the sky," he said.

It comes down to asteroseismology, which is the study of star oscillations. So-called "starquakes" show up as periodic variations in the brightness of the stars. They help asteroseismologists learn about the inner structure of stars in the same way that seismologists use earthquakes to learn about inner Earth.

Travis Metcalfe, a scientist at the National Center for Atmospheric⁴ Research in Colorado, says seismology is like taking an ultrasound image. But, he says, the stars generate their own soundwaves from the boiling motions near the surface. Metcalfe explains that soundwaves travel down into the star and bring information back to the surface, which NASA's Kepler spacecraft records as a flickering⁶ in the brightness of the star.

"To measure the size of a star, we essentially⁷ measure the tone of these musical notes from the starlight," said Travis Metcalfe. "Just as it's easy to hear the difference between a note played on a cello⁸ and a violin, larger stars naturally flicker⁵ in lower tones, while smaller stars flicker in higher tones."??

So, bigger stars sound lower, like a cello, while a smaller star's tone is more like that of a correspondingly smaller violin.

Scientists analyze⁹ a star's soundwaves to learn the size, shape and age of that star, and that information helps them understand the way the relationship between stars and their planets evolve.

The tones of stars' soundwaves are so low that even whales would have a hard time hearing them, but Huber says scientists scaled them to the audible range of the human ear. Once again, here are the sounds of several stars, based on actual frequencies measured by Kepler.

Scientists representing the Kepler Asteroseismic Science Consortium presented these stellar sounds and findings during a teleconference Tuesday from Aarhus University in Denmark.

Astronomers who use Kepler data say the mission helps them understand what will become of our Sun in about 5 billion years, and it helps them identify planet-hosting stars as astronomers search for Earth-like planets.

The Kepler spacecraft was launched in March of 2009. NASA praises the mission as an example of international partnership¹⁰, saying the U.S. space agency provides the spacecraft and data, while hundreds of scientists around the world analyze the findings.

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 accurately   

adv.准确地，精确地

参考例句：

• It is hard to hit the ball accurately.准确地击中球很难。
• Now scientists can forecast the weather accurately.现在科学家们能准确地预报天气。

3 amplitude   

n.广大；充足；振幅

参考例句：

• The amplitude of the vibration determines the loudness of the sound.振动幅度的大小决定声音的大小。
• The amplitude at the driven end is fixed by the driving mechanism.由于驱动机构的作用,使驱动端的振幅保持不变。

4 atmospheric   

adj.大气的，空气的；大气层的；大气所引起的

参考例句：

• Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
• Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。

5 flicker   

vi./n.闪烁，摇曳，闪现

参考例句：

• There was a flicker of lights coming from the abandoned house.这所废弃的房屋中有灯光闪烁。
• At first,the flame may be a small flicker,barely shining.开始时，光辉可能是微弱地忽隐忽现，几乎并不灿烂。

6 flickering   

adj.闪烁的，摇曳的，一闪一闪的

参考例句：

• The crisp autumn wind is flickering away. 清爽的秋风正在吹拂。
• The lights keep flickering. 灯光忽明忽暗。

7 essentially   

adv.本质上，实质上，基本上

参考例句：

• Really great men are essentially modest.真正的伟人大都很谦虚。
• She is an essentially selfish person.她本质上是个自私自利的人。

8 cello   

n.大提琴

参考例句：

• The cello is a member of the violin family.大提琴是提琴家族的一员。
• She plays a melodious cello.她拉着一手悦耳的大提琴。

9 analyze   

vt.分析，解析 (=analyse)

参考例句：

• We should analyze the cause and effect of this event.我们应该分析这场事变的因果。
• The teacher tried to analyze the cause of our failure.老师设法分析我们失败的原因。

10 partnership   

n.合作关系，伙伴关系

参考例句：

• The company has gone into partnership with Swiss Bank Corporation.这家公司已经和瑞士银行公司建立合作关系。
• Martin has taken him into general partnership in his company.马丁已让他成为公司的普通合伙人。