文章来源:未知 文章作者:meng 发布时间:2009-10-30 03:00 字体: [ ]  进入论坛

Astronomers1(天文学家) using the National Science Foundation's Very Large Array (VLA) radio telescope have gained tantalizing2(诱人的) insights into the nature of the most distant object ever observed in the Universe -- a gigantic stellar(星球的) explosion known as a Gamma Ray Burst (GRB). The explosion was detected on April 23 by NASA's Swift satellite, and scientists soon realized that it was more than 13 billion light-years from Earth. It represents an event that occurred 630 million years after the Big Bang, when the Universe was only four percent of its current age of 13.7 billion years.

"This explosion provides an unprecedented3(空前的) look at an era when the Universe was very young and also was undergoing(遭受,经历) drastic(激烈的,猛烈的) changes. The primal4(最初的,原始的) cosmic darkness was being pierced(穿通的) by the light of the first stars and the first galaxies5 were beginning to form. The star that exploded in this event was a member of one of these earliest generations of stars," said Dale Frail6 of the National Radio Astronomy Observatory7.

Astronomers turned telescopes from around the world to study the blast, dubbed8 GRB 090423. The VLA first looked for the object the day after the discovery, detected the first radio waves from the blast a week later, then recorded changes in the object until it faded from view more than two months later.

"It's important to study these explosions with many kinds of telescopes. Our research team combined data from the VLA with data from X-ray and infrared9 telescopes(红外望远镜) to piece together some of the physical conditions of the blast," said Derek Fox of Pennsylvania State University. "The result is a unique look into the very early Universe that we couldn't have gotten any other way," he added.

The scientists concluded that the explosion was more energetic than most GRBs, was a nearly-spherical(球面的,球状的) blast, and that it expanded into a tenuous10(稀薄的,贫乏的) and relatively11 uniform gaseous12 medium(气体介质) surrounding the star.

Astronomers suspect that the very first stars in the Universe were very different -- brighter, hotter, and more massive -- from those that formed later. They hope to find evidence for these giants by observing objects as distant as GRB 090423 or more distant.

"The best way to distinguish these distant, early-generation stars is by studying their explosive deaths, as supernovae(超新星) or Gamma Ray Bursts," said Poonam Chandra, of the Royal Military College of Canada, and leader of the research team. While the data on GRB 090423 don't indicate that it resulted from the death of such a monster star, new astronomical13 tools are coming that may reveal them.

"The Atacama Large Millimeter/submillimeter Array (ALMA), will allow us to pick out these very-distant GRBs more easily so we can target them for intense followup observations. The Expanded Very Large Array, with much greater sensitivity than the current VLA, will let us follow these blasts much longer and learn much more about their energies and environments. We'll be able to look back even further in time," Frail said. Both ALMA and the EVLA are scheduled for completion in 2012.


1 astronomers 569155f16962e086bd7de77deceefcbd     
n.天文学者,天文学家( astronomer的名词复数 )
  • 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 tantalizing 3gnzn9     
adj.逗人的;惹弄人的;撩人的;煽情的v.逗弄,引诱,折磨( tantalize的现在分词 )
  • This was my first tantalizing glimpse of the islands. 这是我第一眼看见的这些岛屿的动人美景。 来自《简明英汉词典》
  • We have only vague and tantalizing glimpses of his power. 我们只能隐隐约约地领略他的威力,的确有一种可望不可及的感觉。 来自英汉非文学 - 历史
3 unprecedented 7gSyJ     
  • The air crash caused an unprecedented number of deaths.这次空难的死亡人数是空前的。
  • A flood of this sort is really unprecedented.这样大的洪水真是十年九不遇。
4 primal bB9yA     
  • Jealousy is a primal emotion.嫉妒是最原始的情感。
  • Money was a primal necessity to them.对于他们,钱是主要的需要。
5 galaxies fa8833b92b82bcb88ee3b3d7644caf77     
星系( galaxy的名词复数 ); 银河系; 一群(杰出或著名的人物)
  • Quasars are the highly energetic cores of distant galaxies. 类星体是遥远星系的极为活跃的核心体。
  • We still don't know how many galaxies there are in the universe. 我们还不知道宇宙中有多少个星系。
6 frail yz3yD     
  • Mrs. Warner is already 96 and too frail to live by herself.华纳太太已经九十六岁了,身体虚弱,不便独居。
  • She lay in bed looking particularly frail.她躺在床上,看上去特别虚弱。
7 observatory hRgzP     
  • 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。
8 dubbed dubbed     
v.给…起绰号( dub的过去式和过去分词 );把…称为;配音;复制
  • Mathematics was once dubbed the handmaiden of the sciences. 数学曾一度被视为各门科学的基础。
  • Is the movie dubbed or does it have subtitles? 这部电影是配音的还是打字幕的? 来自《简明英汉词典》
9 infrared dx0yp     
  • Infrared is widely used in industry and medical science.红外线广泛应用于工业和医学科学。
  • Infrared radiation has wavelengths longer than those of visible light.红外辐射的波长比可见光的波长长。
10 tenuous PIDz8     
  • He has a rather tenuous grasp of reality.他对现实认识很肤浅。
  • The air ten miles above the earth is very tenuous.距离地面十公里的空气十分稀薄。
11 relatively bkqzS3     
  • The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
  • The operation was relatively painless.手术相对来说不痛。
12 gaseous Hlvy2     
  • Air whether in the gaseous or liquid state is a fluid.空气,无论是气态的或是液态的,都是一种流体。
  • Freon exists both in liquid and gaseous states.氟利昂有液态和气态两种形态。
13 astronomical keTyO     
  • He was an expert on ancient Chinese astronomical literature.他是研究中国古代天文学文献的专家。
  • Houses in the village are selling for astronomical prices.乡村的房价正在飙升。