首页
登录
职称英语
In addition to conventional galaxies, the universe contains very dim galaxies th
In addition to conventional galaxies, the universe contains very dim galaxies th
游客
2024-01-12
52
管理
问题
In addition to conventional galaxies, the universe contains very dim galaxies that until recently went unnoticed by astronomers. Possibly as numerous as conventional galaxies, these galaxies have the same general shape and even the same approximate number of stars as a common type of conventional galaxy, the spiral, but tend to be much larger. Because these galaxies’ mass is spread out over larger areas, they have far fewer stars per unit volume than do conventional galaxies. Apparently these low-surface-brightness galaxies, as they are called, take much longer than conventional galaxies to condense their primordial gas and convert it to stars—that is, they evolve much more slowly.
These galaxies may constitute an answer to the long-standing puzzle of the missing baryonic mass in the universe. Baryons—subatomic particles that are generally protons or neutrons—are the source of stellar, and therefore galactic, luminosity, and so their numbers can be estimated based on how luminous galaxies are. However, the amount of helium in the universe, as measured by spectroscopy, suggests that there are far more baryons in the universe than estimates based on galactic luminosity indicate. Astronomers have long speculated that the missing baryonic mass might eventually be discovered in intergalactic space or as some large population of galaxies that are difficult to detect. [br] According to the passage, conventional spiral galaxies differ from low-surface-brightness galaxies in which of the following ways?
选项
A、They have fewer stars than do low-surface-brightness galaxies.
B、They evolve more quickly than low-surface-brightness galaxies.
C、They are more diffuse than low-surface-brightness galaxies.
D、They contain less helium than do low-surface-brightness galaxies.
E、They are larger than low-surface-brightness galaxies.
答案
B
解析
Supporting ideas
This question requires recognizing information that is provided in the passage. The first paragraph describes and compares two types of galaxies: conventional galaxies and dim, or low-surface-brightness, galaxies. It states that dim galaxies have the same approximate number of stars as a common type of conventional galaxy but tend to be larger and more diffuse because their mass is spread over wider areas (lines 4-10). The passage also indicates that dim galaxies take longer than conventional galaxies to convert their primordial gases into stars, meaning that dim galaxies evolve much more slowly than conventional galaxies (lines 10-14), which entails that conventional galaxies evolve more quickly than dim galaxies.
A The passage states that dim galaxies have approximately the same numbers of stars as a common type of conventional galaxy.
B Correct. The passage indicates that dim galaxies evolve much more slowly than conventional galaxies, which entails that conventional galaxies evolve more quickly.
C The passage states that dim galaxies are more spread out, and therefore more diffuse, than conventional galaxies.
D The passage does not mention the relative amounts of helium in the two types of galaxies under discussion.
E The passage states that dim galaxies tend to be much larger than conventional galaxies.
The correct answer is B.
转载请注明原文地址:https://tihaiku.com/zcyy/3357230.html
相关试题推荐
Ajarcontainsonlyred,yellow,andorangemarbles.Ifthereare3red,5yello
Intherectangularquadrantsystemshownabove,whichquadrant,ifany,contains
Acertainjarcontains100jellybeans:50white,30green,10yellow,5red,4
Alargeflowerarrangementcontains3typesofflowers:carnations,lilies,and
Althoughspinachisrichincalcium,italsocontainslargeamountsofoxalicac
Editorialist:Additionalrestrictionsshouldbeplacedondriver’slicensesof
Thetoxinproducedbycertainmarinesnailscontainsvariousproteins,oneofwh
Essayist:Theexistenceofamoralorderintheuniverse—i.e.,anorderinwhi
Ms.Chambersisamongtheforecasterswhopredictthattherateofadditiontoa
Inthe1950’sastronomersweredividedbetweenthosewhobelievedtheuniverseb
随机试题
In1620,102pilgrims,toescape______,sailedtotheNewWorldinashipcalled
现在国家离退休干部、知识分子和工商界人士“告老还乡”,发展家乡,充实家乡。“十三
交换机使能STP时,缺省情况下交换机的优先级为()。A.4096 B.819
修约间隔是1,修约57.46正确的是()。A.57.4 B.57.5 C.
治疗化脓性脑膜炎时头孢曲松钠的剂量是A.50mg/(kg·d) B.200mg
资本约束并不是控制银行操作风险的最好方法,应对操作风险的重要手段是严格的()。
炙甘草汤的功用是A.健脾益气,补肺宁嗽 B.益气健脾,养阴润肺 C.益气健脾
国民经济总体指标不包括()。A:国内生产总值B:工业增加值C:就业率D:通
下列四项中,错误的IP地址有()。 A.60.268.24.168 B.11
基础心理学是研究()。 (A)正常成人心理现象的心理学基础学科 (B
最新回复
(
0
)