黑洞的能量效率惊人
文章来源: 文章作者: 发布时间:2006-09-04 08:48 字体: [ ]  进入论坛
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黑洞的能量效率惊人,如果地球上的汽车引擎效率能像黑洞一般,则一加仑的汽油可跑十亿英哩!
 

Waste not.
Surrounding matter is sucked toward a supermassive black hole, where it is expelled back out at enormous speed in an incredibly efficient process.

Credit: Harvard-Smithsonian Center for Astrophysics

 

High-Mileage Black Holes

By Phil Berardelli
ScienceNOW Daily News
24 April 2006

Astronomers1 have discovered that, deep inside the biggest and brightest galaxies2 in the universe, jets are spewing particles from around black holes in an incredibly energy-efficient manner. If an automobile3 engine worked as well as one of these monsters, it could go more than a billion miles on a gallon of gas.

The surprise is these high-mileage black holes aren't quasars, which are considered the most energetic and efficient bodies in the universe at converting matter to energy . Instead, astronomers have discovered, they are relatively4 old and quiet supermassive black holes that somehow can maintain similar efficiencies while expelling much less energy.

The astronomers used data from the Chandra X-ray Observatory5 to study nine supermassive black holes populating very large elliptical galaxies. In all cases, they found the areas around the black holes to be dim in visible light but quite bright in x-ray wavelengths6. For the nine objects studied, they calculated that the black holes could convert up to 2.5% of the infalling gas and dust to energy--not quite as good as a quasar, which can average 5% or more, but still about 25 times better than the best nuclear power reactors7.

The team also found that the jets produced by the supermassives are streaming outward at incredible speeds--in some cases 95% of the speed of light. "The energy in these jets is absolutely huge," says lead researcher Steven Allen of Stanford University in Palo Alto, California, "about a trillion, trillion, trillion watts8." The findings were announced during a media teleconference today and will be published in an upcoming issue of the Monthly Notices of the Royal Astronomical9 Society.

The question is what process converts the energy from the gas streaming in toward the black holes to the enormous energy in the jets. So far, there is only speculation10, says co-author Christopher Reynolds of the University of Maryland, College Park. One idea is that the rotational11 energy of the supermassives powers the engine.

"We already knew quasars were enormously efficient at making light," says Kimberly Weaver12, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "Now we know black holes in elliptical galaxies are also as efficient at making x-rays." This also could explain why there are few young stars in these galaxies: When the jets collide with the surrounding interstellar gas, they heat it to the point where it cannot condense into new stars.

"Just as with cars, it's critical to know the fuel efficiency of black holes," Allen adds. "Without this information, we cannot figure out what is going on under the hood13, so to speak, or what the engine can do."




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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 galaxies fa8833b92b82bcb88ee3b3d7644caf77     
星系( galaxy的名词复数 ); 银河系; 一群(杰出或著名的人物)
参考例句:
  • 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。
3 automobile rP1yv     
n.汽车,机动车
参考例句:
  • He is repairing the brake lever of an automobile.他正在修理汽车的刹车杆。
  • The automobile slowed down to go around the curves in the road.汽车在路上转弯时放慢了速度。
4 relatively bkqzS3     
adv.比较...地,相对地
参考例句:
  • 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。
5 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。
6 wavelengths 55c7c1db2849f4af018e7824d42c3ff2     
n.波长( wavelength的名词复数 );具有相同的/不同的思路;合拍;不合拍
参考例句:
  • I find him difficult to talk to—we're on completely different wavelengths. 我没法和他谈话,因为我们俩完全不对路。 来自《简明英汉词典》
  • Sunlight consists of different wavelengths of radiation. 阳光由几种不同波长的射线组成。 来自辞典例句
7 reactors 774794d45796c1ac60b7fda5e55a878b     
起反应的人( reactor的名词复数 ); 反应装置; 原子炉; 核反应堆
参考例句:
  • The TMI nuclear facility has two reactors. 三哩岛核设施有两个反应堆。 来自英汉非文学 - 环境法 - 环境法
  • The earliest production reactors necessarily used normal uranium as fuel. 最早为生产用的反应堆,必须使用普通铀作为燃料。
8 watts c70bc928c4d08ffb18fc491f215d238a     
(电力计量单位)瓦,瓦特( watt的名词复数 )
参考例句:
  • My lamp uses 60 watts; my toaster uses 600 watts. 我的灯用60瓦,我的烤面包器用600瓦。
  • My lamp uses 40 watts. 我的灯40瓦。
9 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。
10 speculation 9vGwe     
n.思索,沉思;猜测;投机
参考例句:
  • Her mind is occupied with speculation.她的头脑忙于思考。
  • There is widespread speculation that he is going to resign.人们普遍推测他要辞职。
11 rotational iXdxF     
adj.回转的,轮流的
参考例句:
  • A synchronous motor drives the measuring bob at a constant rotational speed.同步马达驱动测锤以恒速旋转。
  • With some limitations,this is true also of rotational degrees of freedom.在某些限定条件下,这一说法对转动自由度也成立。
12 weaver LgWwd     
n.织布工;编织者
参考例句:
  • She was a fast weaver and the cloth was very good.她织布织得很快,而且布的质量很好。
  • The eager weaver did not notice my confusion.热心的纺织工人没有注意到我的狼狈相。
13 hood ddwzJ     
n.头巾,兜帽,覆盖;v.罩上,以头巾覆盖
参考例句:
  • She is wearing a red cloak with a hood.她穿着一件红色带兜帽的披风。
  • The car hood was dented in.汽车的发动机罩已凹了进去。
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