星体的年龄能通过声波测出
文章来源:未知 文章作者:enread 发布时间:2014-07-04 08:13 字体: [ ]  进入论坛
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Determining the age of stars has long been a challenge for astronomers1. In experiments published in the journal Science, researchers at KU Leuven's Institute for Astronomy show that 'infant' stars can be distinguished2 from 'adolescent' stars by measuring the acoustic3 waves they emit. Stars are often born in clusters, the result of contracting molecular4 clouds of gas and dust particles. As a star evolves from infant to adolescent, gravitational pull causes it to contract. It gets smaller in size and hotter until the core temperature is sufficient to start nuclear burning of hydrogen. At this point, the star stabilizes5 and becomes an 'adult'. It stays this way for vast tracts6 of time.
 
Determining the age of a young star is far from simple, and knowing which molecular cloud a star comes from gives only a vague(模糊的) idea of its age. But researchers have come up with a way to determine the age of stars by measuring their acoustic vibrations7 using ultrasound technology similar to that used in the field of medicine.
 
Acoustic vibrations -- sound waves -- are produced by radiation pressure inside stars. First author Konstanze Zwintz, a postdoctoral researcher at KU Leuven's Institute for Astronomy, and her colleagues studied the vibrations of 34 stars aged8 under 10 million years and sized between one and four times the mass of our sun.
 
"Our data shows that the youngest stars vibrate slower while the stars nearer to adulthood9 vibrate faster. A star's mass has a major impact on its development: stars with a smaller mass evolve slower. Heavy stars grow faster and age more quickly," says Dr. Zwintz.
 
While theoretical physicists10 have posited11 before that young stars vibrate differently than older stars, Zwintz' study is the first to confirm these predications using concrete data from outer space.
 
"We now have a model that more precisely12 measures the age of young stars," says Zwintz. "And we are now also able to subdivide13 young stars according to their various life phases."
 
The researchers studied the nebula14(星云) known commonly as the Christmas Tree Cluster. Their data was obtained from the Canadian MOST satellite and the European CoRoT satellite as well as from ground-based facilities such as the European Southern Observatory15 (ESO) in Chile.


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1 astronomers 569155f16962e086bd7de77deceefcbd     
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 distinguished wu9z3v     
adj.卓越的,杰出的,著名的
参考例句:
  • Elephants are distinguished from other animals by their long noses.大象以其长长的鼻子显示出与其他动物的不同。
  • A banquet was given in honor of the distinguished guests.宴会是为了向贵宾们致敬而举行的。
3 acoustic KJ7y8     
adj.听觉的,声音的;(乐器)原声的
参考例句:
  • The hall has a fine acoustic.这个大厅的传音效果很好。
  • Animals use a whole rang of acoustic, visual,and chemical signals in their systems of communication.动物利用各种各样的听觉、视觉和化学信号来进行交流。
4 molecular mE9xh     
adj.分子的;克分子的
参考例句:
  • The research will provide direct insight into molecular mechanisms.这项研究将使人能够直接地了解分子的机理。
  • For the pressure to become zero, molecular bombardment must cease.当压强趋近于零时,分子的碰撞就停止了。
5 stabilizes 941f717ef460b2f5ae8b72fac9292ecb     
n.(使)稳定, (使)稳固( stabilize的名词复数 )v.(使)稳定, (使)稳固( stabilize的第三人称单数 )
参考例句:
  • The broadbased attachment of the mesenteric root stabilizes the small bowel. 肠系膜根部基底宽阔的附着面使小肠得以稳定。 来自辞典例句
  • The available supply of industrial product and produce stabilizes growth. 工业品与农产品的有效供给稳定增长。 来自互联网
6 tracts fcea36d422dccf9d9420a7dd83bea091     
大片土地( tract的名词复数 ); 地带; (体内的)道; (尤指宣扬宗教、伦理或政治的)短文
参考例句:
  • vast tracts of forest 大片大片的森林
  • There are tracts of desert in Australia. 澳大利亚有大片沙漠。
7 vibrations d94a4ca3e6fa6302ae79121ffdf03b40     
n.摆动( vibration的名词复数 );震动;感受;(偏离平衡位置的)一次性往复振动
参考例句:
  • We could feel the vibrations from the trucks passing outside. 我们可以感到外面卡车经过时的颤动。
  • I am drawn to that girl; I get good vibrations from her. 我被那女孩吸引住了,她使我产生良好的感觉。 来自《简明英汉词典》
8 aged 6zWzdI     
adj.年老的,陈年的
参考例句:
  • He had put on weight and aged a little.他胖了,也老点了。
  • He is aged,but his memory is still good.他已年老,然而记忆力还好。
9 adulthood vKsyr     
n.成年,成人期
参考例句:
  • Some infantile actions survive into adulthood.某些婴儿期的行为一直保持到成年期。
  • Few people nowadays are able to maintain friendships into adulthood.如今很少有人能将友谊维持到成年。
10 physicists 18316b43c980524885c1a898ed1528b1     
物理学家( physicist的名词复数 )
参考例句:
  • For many particle physicists, however, it was a year of frustration. 对于许多粒子物理学家来说,这是受挫折的一年。 来自英汉非文学 - 科技
  • Physicists seek rules or patterns to provide a framework. 物理学家寻求用法则或图式来构成一个框架。
11 posited 5143cf6a131d14610f5f8561619aae61     
v.假定,设想,假设( posit的过去式和过去分词 )
参考例句:
  • Several writers have posited the idea of a universal consciousness. 有几个作者都假设存在普遍意识。 来自辞典例句
  • All cash receipts should be recorded and de-posited daily. 所有的现金收据应该被每日记录和存放。 来自互联网
12 precisely zlWzUb     
adv.恰好,正好,精确地,细致地
参考例句:
  • It's precisely that sort of slick sales-talk that I mistrust.我不相信的正是那种油腔滑调的推销宣传。
  • The man adjusted very precisely.那个人调得很准。
13 subdivide DtGwN     
vt.细分(细区分,再划分,重分,叠分,分小类)
参考例句:
  • You can use sales organizations to subdivide markets into regions.用销售组织将市场细分为区域。
  • The verbs were subdivided into transitive and intransitive categories.动词可细分为及物动词和不及物动词。
14 nebula E55zw     
n.星云,喷雾剂
参考例句:
  • A powerful telescope can resolve a nebula into stars.一架高性能的望远镜能从星云中分辨出星球来。
  • A nebula is really a discrete mass of innumerous stars.一团星云实际上是无数星体不连续的集合体。
15 observatory hRgzP     
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。
TAG标签: waves stars age
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