揭开重恒星的形成之谜
文章来源:未知 文章作者:meng 发布时间:2010-07-15 02:57 字体: [ ]  进入论坛
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"Our observations show a disc surrounding an embryonic1(胚胎的) young, massive star, which is now fully2 formed," says Stefan Kraus, who led the study. "One can say that the baby is about to hatch(孵化) !" The team of astronomers3 looked at an object known by the cryptic4(神秘的,隐藏的) name of IRAS 13481-6124. About twenty times the mass of our Sun and five times its radius5(半径) , the young central star, which is still surrounded by its pre-natal cocoon6(茧,卵囊) , is located in the constellation7(星座) of Centaurus, about 10 000 light-years away.

From archival(档案的) images obtained by the NASA Spitzer Space Telescope as well as from observations done with the APEX8 12-metre submillimetre telescope, astronomers discovered the presence of a jet.

"Such jets are commonly observed around young low-mass stars and generally indicate the presence of a disc," says Kraus.

Circumstellar(环绕恒星的) discs are an essential ingredient(要素,原料) in the formation process of low-mass stars such as our Sun. However, it is not known whether such discs are also present during the formation of stars more massive than about ten solar masses, where the strong light emitted might prevent mass falling onto the star. For instance, it has been proposed that massive stars might form when smaller stars merge9.

In order to discover and understand the properties of this disc, astronomers employed ESO's Very Large Telescope Interferometer (VLTI). By combining light from three of the VLTI's 1.8-metre Auxiliary10 Telescopes with the AMBER11 instrument, this facility allows astronomers to see details equivalent to(等于,相当于) those a telescope with a mirror of 85 metres in diameter would see. The resulting resolution is about 2.4 milliarcseconds, which is equivalent to picking out the head of a screw on the International Space Station, or more than ten times the resolution possible with current visible-light telescopes in space.

With this unique capability12, complemented13 by observations done with another of ESO's telescopes, the 3.58-metre New Technology Telescope at La Silla, Kraus and colleagues were able to detect a disc around IRAS 13481-6124.

"This is the first time we could image the inner regions of the disc around a massive young star", says Kraus. "Our observations show that formation works the same for all stars, regardless of mass."

The astronomers conclude that the system is about 60 000 years old, and that the star has reached its final mass. Because of the intense light of the star — 30 000 times more luminous14(发光的,明亮的) than our Sun — the disc will soon start to evaporate(蒸发,脱水) . The flared15 disc extends to about 130 times the Earth–Sun distance — or 130 astronomical16 units (AU) — and has a mass similar to that of the star, roughly twenty times the Sun. In addition, the inner parts of the disc are shown to be devoid17 of dust.

"Further observations with the Atacama Large Millimeter/submillimeter Array (ALMA), currently being constructed in Chile, could provide much information on these inner parts, and allow us to better understand how baby massive stars became heavy," concludes Kraus.



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1 embryonic 58EyK     
adj.胚胎的
参考例句:
  • It is still in an embryonic stage.它还处于萌芽阶段。
  • The plan,as yet,only exists in embryonic form.这个计划迄今为止还只是在酝酿之中。
2 fully Gfuzd     
adv.完全地,全部地,彻底地;充分地
参考例句:
  • The doctor asked me to breathe in,then to breathe out fully.医生让我先吸气,然后全部呼出。
  • They soon became fully integrated into the local community.他们很快就完全融入了当地人的圈子。
3 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》
4 cryptic yyDxu     
adj.秘密的,神秘的,含义模糊的
参考例句:
  • She made a cryptic comment about how the film mirrored her life.她隐晦地表示说这部电影是她人生的写照。
  • The new insurance policy is written without cryptic or mysterious terms.新的保险单在编写时没有隐秘条款或秘密条款。
5 radius LTKxp     
n.半径,半径范围;有效航程,范围,界限
参考例句:
  • He has visited every shop within a radius of two miles.周围两英里以内的店铺他都去过。
  • We are measuring the radius of the circle.我们正在测量圆的半径。
6 cocoon 2nQyB     
n.茧
参考例句:
  • A cocoon is a kind of silk covering made by an insect.蚕茧是由昆虫制造的一种由丝组成的外包层。
  • The beautiful butterfly emerged from the cocoon.美丽的蝴蝶自茧中出现。
7 constellation CptzI     
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。
8 apex mwrzX     
n.顶点,最高点
参考例句:
  • He reached the apex of power in the early 1930s.他在三十年代初达到了权力的顶峰。
  • His election to the presidency was the apex of his career.当选总统是他一生事业的顶峰。
9 merge qCpxF     
v.(使)结合,(使)合并,(使)合为一体
参考例句:
  • I can merge my two small businesses into a large one.我可以将我的两家小商店合并为一家大商行。
  • The directors have decided to merge the two small firms together.董事们已决定把这两家小商号归并起来。
10 auxiliary RuKzm     
adj.辅助的,备用的
参考例句:
  • I work in an auxiliary unit.我在一家附属单位工作。
  • The hospital has an auxiliary power system in case of blackout.这家医院装有备用发电系统以防灯火管制。
11 amber LzazBn     
n.琥珀;琥珀色;adj.琥珀制的
参考例句:
  • Would you like an amber necklace for your birthday?你过生日想要一条琥珀项链吗?
  • This is a piece of little amber stones.这是一块小小的琥珀化石。
12 capability JsGzZ     
n.能力;才能;(pl)可发展的能力或特性等
参考例句:
  • She has the capability to become a very fine actress.她有潜力成为杰出演员。
  • Organizing a whole department is beyond his capability.组织整个部门是他能力以外的事。
13 complemented ef190f44a2dd6967f0c5c8104e74e707     
有补助物的,有余格的
参考例句:
  • The excellent menu is complemented by a good wine list. 佳肴佐以美酒,可称完美无缺。
  • In vitro analysis must be complemented by studies of the virus replication cycle in plants. 体外的分析必须辅之以植物体内病毒复制周期的研究。
14 luminous 98ez5     
adj.发光的,发亮的;光明的;明白易懂的;有启发的
参考例句:
  • There are luminous knobs on all the doors in my house.我家所有门上都安有夜光把手。
  • Most clocks and watches in this shop are in luminous paint.这家商店出售的大多数钟表都涂了发光漆。
15 Flared Flared     
adj. 端部张开的, 爆发的, 加宽的, 漏斗式的 动词flare的过去式和过去分词
参考例句:
  • The match flared and went out. 火柴闪亮了一下就熄了。
  • The fire flared up when we thought it was out. 我们以为火已经熄灭,但它突然又燃烧起来。
16 astronomical keTyO     
adj.天文学的,(数字)极大的
参考例句:
  • 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。
17 devoid dZzzx     
adj.全无的,缺乏的
参考例句:
  • He is completely devoid of humour.他十分缺乏幽默。
  • The house is totally devoid of furniture.这所房子里什么家具都没有。
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