A team of astronomers led by Tomoharu Oka, a professor at Keio University in Japan, has found an enigmatic gas cloud, called CO-0.40-0.22, only 200 light years away from the center of the Milky Way. What makes CO-0.40-0.22 unusual is its surprisingly wide velocity dispersion: the cloud contains gas with a very wide range of speeds. The team found this mysterious feature with two radio telescopes, the Nobeyama 45-m Telescope inJapan and the ASTE Telescope in Chile, both operated by the National Astronomical Observatory of Japan. To investigate the detailed structure, the team observed CO-0.40-0.22 with the Nobeyama 45-m Telescope again to obtain 21 emission linesfrom 18 molecules. The results show that the cloud has an elliptical shape and consists of two components: a compact but low density component with a very wide velocity dispersion of 100 km/s, and a dense component extending 10 light years with a narrow velocity dispersion.

What makes this velocity dispersion so wide? There are no holes inside of the cloud.Also, X-ray and infrared observations did not find any compact objects. These features indicate that the velocity dispersion is not caused by a local energy input, such as supernova explosions.

The team performed a simple simulation of gas clouds flung by a strong gravity source.In the simulation, the gas clouds are first attracted by the source and theirspeeds increase as they approach it, reaching maximum at the closest point tothe object. After that the clouds continue past the object and their speedsdecrease. The team found that a model using a gravity source with 100 thousandtimes the mass of the Sun inside an area with a radius of 0.3 light years provided the best fit to the observed data. "Considering the fact that no compact objects are seen in X-ray or infrared observations," Oka, the lead author of the paper that appeared in the Astrophysical Journal Letters,explains "as far as we know, the best candidate for the compact massive object is a black hole."

If that is the case, this is the first detection of an intermediate mass black hole.Astronomers already know about two sizes of black holes: stellar-mass black holes, formed after the gigantic explosions of very massive stars; and supermassive black holes (SMBH) often found at the centers of galaxies. Themass of SMBH ranges from several million to billions of times the mass of the Sun. A number of SMBHs have been found, but no one knows how the SMBHs are formed. One idea is that they are formed from mergers of many intermediate mass black holes. But this raises a problem because so far no firm observational evidence for intermediate mass black holes has been found. If the cloud CO-0.40-0.22, located only 200 light years away from Sgr A* (the 400 millionsolar mass SMBH at the center of the Milky Way), contains an intermediate mass black hole, it might support the intermediate mass black hole merger scenario of SMBH evolution.

These results open a new way to search for black holes with radio telescopes. Recent observations have revealed that there are a number of wide-velocity-dispersion compact clouds similar to CO-0.40-0.22. The team proposes that some of those clouds might contain black holes. A study suggested that there are 100 million black holes in the Milky Way Galaxy, but X-ray observations have only found dozens so far. Most of the black holes may be "dark" and verydifficult to see directly at any wavelength. "Investigations of gas motion with radio telescopes may provide a complementary way to search for dark blackholes" said Oka. "The on-going wide area survey observations of the Milky Way with the Nobeyama 45-m Telescope and high-resolution observations of nearby galaxies using the Atacama Large Millimeter/submillimeter Array (ALMA) have the potential to increase the number of black hole candidates dramatically."

 

1 astronomers

n.天文學(xué)者，天文學(xué)家(astronomer的名詞復(fù)數(shù) )

參考例句：

? Astronomers can accurately foretell thedate,time,and length of future eclipses. 天文學(xué)家能精確地預(yù)告未來日食月食的日期、時(shí)刻和時(shí)長。 來自《簡明英漢詞典》

?  Astronomers used to ask why only Saturnhas rings. 天文學(xué)家們過去一直感到奇怪，為什么只有土星有光環(huán)。來自《簡明英漢詞典》

2 milky

adj.牛奶的，多奶的；乳白色的

參考例句：

? Alexander always has milky coffee atlunchtime.亞歷山大總是在午餐時(shí)喝摻奶的咖啡。

?  I like a hot milky drink at bedtime.我喜歡睡前喝杯熱奶飲料。

3 velocity

n.速度，速率

參考例句：

? Einstein's theory links energy with massand velocity of light.愛因斯坦的理論把能量同質(zhì)量和光速聯(lián)系起來。

? The velocity of light is about 300000kilometres per second.光速約為每秒300000公里。

4 astronomical

adj.天文學(xué)的，（數(shù)字）極大的

參考例句：

? He was an expert on ancient Chineseastronomical literature.他是研究中國古代天文學(xué)文獻(xiàn)的專家。

? Houses in the village are selling forastronomical prices.鄉(xiāng)村的房價(jià)正在飆升。

5 observatory

n.天文臺，氣象臺，瞭望臺，觀測臺

參考例句：

? Guy's house was close to the observatory.蓋伊的房子離天文臺很近。

? Officials from Greenwich Observatory havethe clock checked twice a day.格林威治天文臺的職員們每天對大鐘檢查兩次。

6 detailed

adj.詳細(xì)的，詳盡的，極注意細(xì)節(jié)的，完全的

參考例句：

?  He had made a detailed study of theterrain.他對地形作了縝密的研究。

?  A detailed list of our publications isavailable on request.我們的出版物有一份詳細(xì)的目錄備索。

7 emission

n.發(fā)出物，散發(fā)物；發(fā)出，散發(fā)

參考例句：

? Rigorous measures will be taken to reducethe total pollutant emission.采取嚴(yán)格有力措施，降低污染物排放總量。

?  Finally,the way to effectively controlparticulate emission is pointed out.最后，指出有效降低顆粒排放的方向。

8 molecules

分子( molecule的名詞復(fù)數(shù) )

參考例句：

?  The structure of molecules can be seenunder an electron microscope. 分子的結(jié)構(gòu)可在電子顯微鏡下觀察到。

? Inside the reactor the large moleculesare cracked into smaller molecules. 在反應(yīng)堆里，大分子裂變?yōu)樾》肿印?/span>

9 component

n.組成部分，成分，元件；adj.組成的，合成的

參考例句：

? Each component is carefully checkedbefore assembly.每個零件在裝配前都經(jīng)過仔細(xì)檢查。

? Blade and handle are the component partsof a knife.刀身和刀柄是一把刀的組成部分。

10 components

（機(jī)器、設(shè)備等的）構(gòu)成要素，零件，成分； 成分( component的名詞復(fù)數(shù) )； [物理化學(xué)]組分； [數(shù)學(xué)]分量； （混合物的）組成部分

參考例句：

? the components of a machine 機(jī)器部件

?  Our chemistry teacher often reduces acompound to its components in lab. 在實(shí)驗(yàn)室中化學(xué)老師常把化合物分解為各種成分。

11 density

n.密集，密度，濃度

參考例句：

? The population density of that country is685 per square mile.那個國家的人口密度為每平方英里685人。

? The region has a very high populationdensity.該地區(qū)的人口密度很高。

12 dense

a.密集的，稠密的，濃密的；密度大的

參考例句：

? The general ambushed his troops in thedense woods. 將軍把部隊(duì)埋伏在濃密的樹林里。

? The path was completely covered by thedense foliage. 小路被樹葉厚厚地蓋了一層。

13 infrared

adj./n.紅外線(的)

參考例句：

? Infrared is widely used in industry andmedical science.紅外線廣泛應(yīng)用于工業(yè)和醫(yī)學(xué)科學(xué)。

? Infrared radiation has wavelengths longerthan those of visible light.紅外輻射的波長比可見光的波長長。

14 input

n.輸入(物)；投入；vt.把(數(shù)據(jù)等)輸入計(jì)算機(jī)

參考例句：

?  I will forever be grateful for hisconsiderable input.我將永遠(yuǎn)感激他的大量投入。

?  All this information had to be input ontothe computer.所有這些信息都必須輸入計(jì)算機(jī)。

15radius

n.半徑，半徑范圍；有效航程，范圍，界限

參考例句：

? He has visited every shop within a radiusof two miles.周圍兩英里以內(nèi)的店鋪他都去過。

?  We are measuring the radius of thecircle.我們正在測量圓的半徑。

16 galaxies

星系( galaxy的名詞復(fù)數(shù) )； 銀河系； 一群（杰出或著名的人物）

參考例句：

? Quasars are the highly energetic cores ofdistant galaxies. 類星體是遙遠(yuǎn)星系的極為活躍的核心體。

? We still don't know how many galaxiesthere are in the universe. 我們還不知道宇宙中有多少個星系。

17 merger

n.企業(yè)合并，并吞

參考例句：

?  Acceptance of the offer is the first stepto a merger.對這項(xiàng)提議的贊同是合并的第一步。

? Shareholders will be voting on the mergerof the companies.股東們將投票表決公司合并問題。

18 mergers

n.（兩個公司的）合并(merger的名詞復(fù)數(shù) )

參考例句：

? Mergers fall into three categories:horizontal, vertical, and conglomerate. 合并分為以下三種：橫向合并，縱向合并和混合合并。 來自辭典例句

?  Many recent mergers are concentratedwithin specific industries, particularly in retailing, airlines andcommunications. 現(xiàn)代許多合并企業(yè)集中進(jìn)行某些特定業(yè)務(wù)，在零售業(yè)、民航和通訊業(yè)中更是如此。來自英漢非文學(xué) - 政府文件

19 scenario

n.劇本，腳本；概要

參考例句：

? But the birth scenario is not completelyaccurate.然而分娩腳本并非完全準(zhǔn)確的。

? This is a totally different scenario.這是完全不同的劇本。

20 galaxy

n.星系；銀河系；一群(杰出或著名的人物)

參考例句：

? The earth is one of the planets in theGalaxy.地球是銀河系中的星球之一。

? The company has a galaxy of talent.該公司擁有一批優(yōu)秀的人才。

21 wavelength

n.波長

參考例句：

? The authorities were unable to jam thiswavelength.當(dāng)局無法干擾這一波長。

?  Radio One has broadcast on thiswavelength for years.廣播1臺已經(jīng)用這個波長廣播多年了。

22 investigations

（正式的）調(diào)查(investigation的名詞復(fù)數(shù) )；偵查； 科學(xué)研究； 學(xué)術(shù)研究

參考例句：

? His investigations were intensive andthorough but revealed nothing. 他進(jìn)行了深入徹底的調(diào)查，但沒有發(fā)現(xiàn)什么。

? He often sent them out to makeinvestigations. 他常常派他們出去作調(diào)查。