国家地理-2008-05-03 Planetary Life After Death 浴火重生的行星

Like a phoenix¹ rising from the ashes, astronomers² have found a whole new solar system may be forming in the wake of a star's violent death.

This is the Hidden Universe of the Spitzer Space Telescope, exploring the mysteries of infrared³ astronomy with your host Dr. Robert Hurt.

When a massive star reaches the end of the line, it ''does not go gentle into that good night''. It becomes a supernova, an explosion so bright that it briefly⁴ outshines everything else in the galaxy⁵. Most of the heavy elements that make up planets, and even people, are forged in the nuclear furnaces of such explosions. Here we see heavy elements in the Cassiopeia A supernova remnant blowing back into the galaxy and mingling⁶ with interstellar gases. The next generation of baby stars forms from this material now enriched with building blocks for growing new solar systems and planets.

But what of the star that went supernova? Its core still remains⁷ in the form of a pulsar. This stellar corpse⁸ is tiny and dense⁹, squeezing about 1.5 times the mass of the Sun into an object a mere¹⁰ 10 miles across.

A team led by Dr. Deepto Chakrabarty at the Massachusetts Institute of Technology has found that even a dead pulsar might play host to a whole new generation of planet formation. They studied a once-massive star that went supernova about 100,000 years ago. In the process it likely wiped out any existing planets. While most of the star-stuff blew off into space, a little bit fell back under the pull of gravity. Dr. Chakrabarty explains. "If the original massive star was spinning fast enough then that material won't fall directly back onto the neutron¹¹ star, but may instead form a disk, and so what we think we've found is a disk of this debris¹² material that's left over from the explosion that formed the neutron star.

This disk has about 10 times the Earth's mass and looks very much like ones that produce planets around young stars. Moreover, it may help solve a recent planet-making mystery. In 1992, astronomers found the first planets outside our solar system, which were orbiting an older pulsar. But where did they come from? Could they have formed after their star went supernova? The discovery of a planet forming disk around a younger pulsar makes this likely. It seems new planets can arise from the ashes of their own star's death.

However pulsar planets are pretty hostile real estate for life. Pulsars provide little light or heat and would bathe these worlds in intense radiation. A nuclear waste dump at the South Pole might actually be a little more pleasant.

1. end of the road/line
n. phr. The final result or end (as of a way of action or behavior); the condition that comes when you can do no more.

2. Do Not Go Gentle Into That Good Night
a villanelle composed in 1951, is considered to be among the finest works by Welsh poet Dylan Thomas (1914–1953). Originally published in the journal Botteghe Oscure in 1951, it also appeared as part of the collection "In Country Sleep." It is one of his most-quoted works. It was written for his dying father.

3. supernova 超新星
a very large exploding star

4. Cassiopeia 仙后座
A W-shaped constellation¹³ in the Northern Hemisphere between Andromeda and Cepheus.

5. remnant
a small part of something that remains after the rest of it has been used, destroyed, or eaten

6. pulsar: 脉冲星
star that cannot be seen but can be detected by pulsating¹⁴ radio signals

7. wipe out
To remove, kill, or destroy completely

8. neutron star: 中子星
A celestial¹⁵ body consisting of the superdense remains of a massive star that has collapsed¹⁶ with sufficient force to push all of its electrons into the nuclei¹⁷ that they orbit, thus leaving only neutrons¹⁸, and having a powerful gravitational attraction from which only neutrinos and high-energy photons can escape, rendering¹⁹ the body detectable²⁰ only by x-ray.

1 phoenix   

n.凤凰，长生(不死)鸟；引申为重生

参考例句：

• The airline rose like a phoenix from the ashes.这家航空公司又起死回生了。
• The phoenix worship of China is fetish worship not totem adoration.中国凤崇拜是灵物崇拜而非图腾崇拜。

2 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》

3 infrared   

adj./n.红外线(的)

参考例句：

• 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。

4 briefly   

adv.简单地，简短地

参考例句：

• I want to touch briefly on another aspect of the problem.我想简单地谈一下这个问题的另一方面。
• He was kidnapped and briefly detained by a terrorist group.他被一个恐怖组织绑架并短暂拘禁。

5 galaxy   

n.星系；银河系；一群(杰出或著名的人物)

参考例句：

• The earth is one of the planets in the Galaxy.地球是银河系中的星球之一。
• The company has a galaxy of talent.该公司拥有一批优秀的人才。

6 mingling   

adj.混合的

参考例句：

• There was a spring of bitterness mingling with that fountain of sweets. 在这个甜蜜的源泉中间，已经掺和进苦涩的山水了。
• The mingling of inconsequence belongs to us all. 这场矛盾混和物是我们大家所共有的。

7 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

8 corpse   

n.尸体，死尸

参考例句：

• What she saw was just an unfeeling corpse.她见到的只是一具全无感觉的尸体。
• The corpse was preserved from decay by embalming.尸体用香料涂抹以防腐烂。

9 dense   

a.密集的，稠密的，浓密的；密度大的

参考例句：

• The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
• The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。

10 mere   

adj.纯粹的；仅仅，只不过

参考例句：

• That is a mere repetition of what you said before.那不过是重复了你以前讲的话。
• It's a mere waste of time waiting any longer.再等下去纯粹是浪费时间。

11 neutron   

n.中子

参考例句：

• Neutron is neutral and slightly heavier than the proton.中子是中性的，比质子略重。
• Based on the neutron energy,the value of weighting factor was given.根据中子能量给出了相应的辐射权重因子的数值。

12 debris   

n.瓦砾堆，废墟，碎片

参考例句：

• After the bombing there was a lot of debris everywhere.轰炸之后到处瓦砾成堆。
• Bacteria sticks to food debris in the teeth,causing decay.细菌附着在牙缝中的食物残渣上，导致蛀牙。

13 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。

14 pulsating   

adj.搏动的，脉冲的v.有节奏地舒张及收缩( pulsate的现在分词 )；跳动；脉动；受（激情）震动

参考例句：

• Lights were pulsating in the sky. 天空有闪烁的光。
• Spindles and fingers moved so quickly that the workshop seemed to be one great nervously-pulsating machine. 工作很紧张，全车间是一个飞快的转轮。 来自子夜部分

15 celestial   

adj.天体的；天上的

参考例句：

• The rosy light yet beamed like a celestial dawn.玫瑰色的红光依然象天上的朝霞一样绚丽。
• Gravity governs the motions of celestial bodies.万有引力控制着天体的运动。

16 collapsed   

adj.倒塌的

参考例句：

• Jack collapsed in agony on the floor. 杰克十分痛苦地瘫倒在地板上。
• The roof collapsed under the weight of snow. 房顶在雪的重压下突然坍塌下来。

17 nuclei   

n.核

参考例句：

• To free electrons, something has to make them whirl fast enough to break away from their nuclei. 为了释放电子，必须使电子高速旋转而足以摆脱原子核的束缚。
• Energy is released by the fission of atomic nuclei. 能量是由原子核分裂释放出来的。

18 neutrons   

n.中子( neutron的名词复数 )

参考例句：

• The neutrons and protons form the core of the atom. 中子和质子构成了原子核。 来自《简明英汉词典》
• When an atom of U235 is split,several neutrons are set free. 一个铀235原子分裂时，释放出几个中子。 来自《简明英汉词典》

19 rendering   

n.表现，描写

参考例句：

• She gave a splendid rendering of Beethoven's piano sonata.她精彩地演奏了贝多芬的钢琴奏鸣曲。
• His narrative is a super rendering of dialect speech and idiom.他的叙述是方言和土语最成功的运用。

20 detectable   

adj.可发觉的；可查明的

参考例句：

• The noise is barely detectable by the human ear.人的耳朵几乎是察觉不到这种噪音的。
• The inflection point at this PH is barely detectable.在此PH值下，拐点不易发现。