首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Until recently most astronomers believed that the space between the galaxies in our universe was a near perfect vacuum. This ort
Until recently most astronomers believed that the space between the galaxies in our universe was a near perfect vacuum. This ort
admin
2019-02-01
62
问题
Until recently most astronomers believed that the space between the galaxies in our universe was a near perfect vacuum. This orthodox view of the universe is now being challenged by astronomers who believe that a heavy "rain" of gas is falling into many galaxies from the supposedly empty space around them. The gas apparently con- denses into a collection of small stars, each a little larger than the planet Jupiter. These stars vastly outnumber the other stars in a given galaxy. The amount of " intergalactic rainfall" into some of these galaxies has been enough to double their mass in the time since they formed. Scientists have begun to suspect that this intergalactic gas is probably a mixture of gases left over from the "big bang" when the galaxies were formed and gas was forced out of galaxies by supernova explosions.
It is well known that when gas is cooled at a constant pressure its volume decreases. Thus, the physicist Fabian reasoned that as intergalactic gas cools, the cooler gas shrinks inward toward the center of the galaxy. Meanwhile its place is taken by hotter intergalactic gas from farther out on the edge of the galaxy, which cools as it is compressed and flows into the galaxy. The net result is a continuous flow of gas, starting as hot gases in inter galactic space and ending as a drizzle of cool gas called a "cooling flow," falling into the central galaxy.
A fairly heretical idea in the 1970’s, the cooling-flow theory gained sup- port when Fabian observed a cluster of galaxies in the constellation Perseus and found the central galaxy, NGC 1275, to be a strange-looking object with irregular, thin strands of gas radiating from it. According to previous speculation, these strands were gases that had been blown out by an explosion in the galaxy. Fabian, however, disagreed. Because the strands of gas radiating from NGC 1275 are visible in optical photographs, Fabian suggested that such strands consisted not of gas blown out of the galaxy but of cooling flows of gas streaming inward. He noted that the wavelengths of the radiation emitted by a gas would changes as the gas cooled, so that as the gas flowed into the galaxy and became cooler, it would emit not x-rays, but visible light, like that which was captured in the photographs. Fabian’s hypothesis was supported by Canizares’ determination in 1982 that most of the gas in the Perseus cluster was at a temperature of 80 mil lion degrees Kelvin, whereas the gas immediately surrounding NGC 1275(the subject of the photographs)was at one-tenth this temperature.
It can be inferred from the passage that, if Fabian is correct, gas in the peripheral regions of a galaxy cluster
选项
A、streams outward into intergalactic space.
B、is hotter than gas in the central regions of the galaxy.
C、is composed primarily of gas left over from the big bang.
D、results in the creation of unusually large stars.
E、expands to increase the size of the galaxy.
答案
B
解析
如果F的观点正确,一个星系周围区域的气体有何特点?A.向星际间释放。和F的观点相反。从文章第二段F的推理过程可得:他认为星系间的热气体向星系中心流动,在这个过程中气体也逐渐变冷(L25—37)。B.正确。比星系中心的气体要热。推理见A。C.“big bang”和F的推理过程毫无关系。D.“unusually large stars”原文未提。E.“increase the size”原文无。
转载请注明原文地址:https://kaotiyun.com/show/Y1kO777K
本试题收录于:
GMAT VERBAL题库GMAT分类
0
GMAT VERBAL
GMAT
相关试题推荐
He______thathecouldcreatelivefishoutofchemicals.
Alltheusefulenergyatthesurfaceoftheearthcomesfromtheactivityofthesun.Thesunheatsandfeedscreaturesandmank
Weallknowthatitispossibleforordinarypeopletomaketheirhomesontheequator(道),althoughoftentheymayfeeluncomfo
"Helicopterparenting"describesastyleofraisingchildrenwhereparentsareover-protectiveanddotoomuch.Thetermwasuse
Spending50minuteswithacellphoneclosetoyourearisenoughtochangebraincellactivityinthepartofthebrainclosest
Americansusetheterm"collegestudents"tomeanstudentseitherincollegesoruniversities.Notonlythat,Americansalmost
Someunionofficialshavesuggestedthatwomenshouldreturnhomebecause______.Fromthepassagewecansee"phasedemploymen
Thevitaminsnecessaryforahealthybodyarenormallysuppliedbyagoodmixeddiet(饮食),includingavarietyoffruitsandgre
In1863,AbrahamLincolnwas______.WhichofthefollowingstatementsisNOTtrueaccordingtothepassage?
Anthropologistsoncethoughtthattheancestorsofmodernhumansbegantowalkuprightbecauseitfreedtheirhandstousestone
随机试题
背景资料:某房地产开发公司与某施工单位签订了一份价款为1000万元的建筑工程施工合同,合同工期为7个月。工程价款约定如下:(1)工程预付款为合同价的10%;(2)工程预付款扣回的时间及比例:自工程款(不含工程预付款)支付至合同价款的60%后,开始从
如图A-8所示,()表示仪表电动管路。
下面哪个部位出血可在短时间内死亡
心脏病孕妇,在妊娠与产褥期间,加重心脏负担的原因哪项是错误的
A.一种药物能使另一种药物的功效降低或消失的配伍B.性能功效有部分共性的药物配合应用C.一种药的毒副作用能被另一种药物减轻或消除的配伍D.一种药物能减轻或消除另一种药毒性的配伍E.性能功效相似药物配合应用,可以增强原有疗效的配伍相恶的定义是
通过抑制细菌DNA依赖的RNA聚合酶而发挥作用,口服后尿液呈橘红色的药物是
患者男性,28岁,左胸外伤后肋骨骨折,极度呼吸困难,发绀、烦躁不安。体检:脉搏细速,血压84/62mmHg,皮肤湿冷,气管右移,颈静脉充盈,头颈部和右胸皮下气肿,左胸廓饱满、肋间隙增宽、呼吸幅度降低,叩诊呈鼓音,右肺呼吸音消失。最可能的诊断是
所谓特种作业人员,是指直接从事特种作业者,其作业的场所、操作的设备、操作内容具有较大的危险性,容易发生伤亡事故,或者容易对操作者本人、他人以及周围设施的安全造成重大危害。
室内燃气管道安装,燃气管道采用螺纹连接时,煤气管可选用()为填料。
简述幼儿园的保教目标。
最新回复
(
0
)