文章来源:未知 文章作者:meng 发布时间:2010-11-01 03:27 字体: [ ]  进入论坛

Dramatic flares1 and bursts of energy - activity previously2 thought reserved for only the strongest magnetized pulsars(脉冲星) - has been observed emanating3 from(放射,发源于) a weakly magnetised, slowly rotating pulsar. The international team of astrophysicists(天体物理学家) who made the discovery believe that the source of the pulsar's power may be hidden deep within its surface. Pulsars, or neutron4 stars, are the collapsed5 remains6 of massive stars. Although they are on average only about 30km in diameter, they have hugely powerful surface magnetic fields, billions of times that of our Sun.

The most extreme kind of pulsars have a surface magnetic field 50-1000 times stronger than normal and emit powerful flares of gamma rays and X-rays. Named magnetars (which stands for "magnetic stars") by astronomers7, their huge magnetic fields are thought to be the ultimate source of power for the bursts of gamma rays.

Theoretical studies indicate that in magnetars the internal field is actually stronger than the surface field, a property which can deform8(变形) the crust and propagate(繁殖) outwards9. The decay of the magnetic field leads to the production of steady and bursting X-ray emission10 through the heating of the neutron star crust or the acceleration11 of particles.

Now, research published today in Science, suggests that the same power source can also work for weaker, non-magnetar, pulsars. The observations, which were made by NASA's Chandra and Swift X-ray observatories12 of the neutron star SGR 0418, may indicate the presence of a huge internal magnetic field in these seemingly less powerful pulsars, which is not matched by their surface magnetic field.

"We have now discovered bursts and flares, i.e. magnetar-like activity, from a new pulsar whose magnetic field is very low," said Dr Silvia Zane, from UCL's (University College London) Mullard Space Science Laboratory, and an author of the research.

Pulsars are highly magnetized, and as they rotate winds of high-energy particles carry energy away from the star, causing the rotation13 rate of the star to gradually decrease. What sets SGR 0418 apart from similar neutron stars is that, unlike those stars that are observed to be gradually rotating more slowly, careful monitoring of SGR 0418 over a span of 490 days has revealed no evidence that its rotation is decreasing.

"It is the very first time this has been observed and the discovery poses the question of where the powering mechanism14 is in this case. At this point, we are also interested in how many of the other normal, low field neutron stars that populate the galaxy15 can at some point wake up and manifest themselves as a flaring16 source," said Dr Zane.

A crucial question is how large an imbalance can be maintained between the surface and interior magnetic fields. SGR 0418 represents an important test case.

"If further observations by Chandra and other satellites push the surface magnetic field limit lower, then theorists may have to dig deeper for an explanation of this enigmatic(神秘的) object," said Dr Nanda Rea, Institut de Ciencies de l'Espai (ICE-CSIC, IEEC) in Barcelona, who led the discovery.


1 flares 2c4a86d21d1a57023e2985339a79f9e2     
n.喇叭裤v.(使)闪耀( flare的第三人称单数 );(使)(船舷)外倾;(使)鼻孔张大;(使)(衣裙、酒杯等)呈喇叭形展开
  • The side of a ship flares from the keel to the deck. 船舷从龙骨向甲板外倾。 来自《简明英汉词典》
  • He's got a fiery temper and flares up at the slightest provocation. 他是火爆性子,一点就着。 来自《现代汉英综合大词典》
2 previously bkzzzC     
  • The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
  • Let me digress for a moment and explain what had happened previously.让我岔开一会儿,解释原先发生了什么。
3 emanating be70e0c91e48568de32973cab34020e6     
v.从…处传出,传出( emanate的现在分词 );产生,表现,显示
  • Even so, there is a slight odour of potpourri emanating from Longfellow. 纵然如此,也还是可以闻到来自朗费罗的一种轻微的杂烩的味道。 来自辞典例句
  • Many surface waters, particularly those emanating from swampy areas, are often colored to the extent. 许多地表水,特别是由沼泽地区流出的地表水常常染上一定程度的颜色。 来自辞典例句
4 neutron neutron     
  • 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。
5 collapsed cwWzSG     
  • 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。
6 remains 1kMzTy     
  • 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。
7 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》
8 deform L9Byo     
  • Shoes that are too tight deform the feet.(穿)太紧的鞋子会使脚变形。
  • Ice crystals begin to deform measurably.冰晶就产生某种程度的变形了。
9 outwards NJuxN     
  • Does this door open inwards or outwards?这门朝里开还是朝外开?
  • In lapping up a fur,they always put the inner side outwards.卷毛皮时,他们总是让内层朝外。
10 emission vjnz4     
  • Rigorous measures will be taken to reduce the total pollutant emission.采取严格有力措施,降低污染物排放总量。
  • Finally,the way to effectively control particulate emission is pointed out.最后,指出有效降低颗粒排放的方向。
11 acceleration ff8ya     
  • All spacemen must be able to bear acceleration.所有太空人都应能承受加速度。
  • He has also called for an acceleration of political reforms.他同时呼吁加快政治改革的步伐。
12 observatories d730b278442c711432218e89314e2a09     
n.天文台,气象台( observatory的名词复数 )
  • John Heilbron, The Sun in the Church: Cathedrals as Solar Observatories, 3-23. 约翰.海耳布隆,《教会里的太阳:教堂即太阳观测台》,第3-23页。 来自互联网
  • Meteorologists use satellites, land observatories and historical data to provide information about the weather. 气象学家使用卫星、上天文台和历史资料来提供有关天气的信息。 来自互联网
13 rotation LXmxE     
  • Crop rotation helps prevent soil erosion.农作物轮作有助于防止水土流失。
  • The workers in this workshop do day and night shifts in weekly rotation.这个车间的工人上白班和上夜班每周轮换一次。
14 mechanism zCWxr     
  • The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
  • The mechanism of the machine is very complicated.这台机器的结构是非常复杂的。
15 galaxy OhoxB     
  • 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。
16 flaring Bswzxn     
  • A vulgar flaring paper adorned the walls. 墙壁上装饰着廉价的花纸。
  • Goebbels was flaring up at me. 戈塔尔当时已对我面呈愠色。
TAG标签: energy stars pulsar