首页
登录
职称英语
Because of its precision, the Cepheid-variable method of correlating
Because of its precision, the Cepheid-variable method of correlating
游客
2024-01-11
34
管理
问题
Because of its precision, the Cepheid-variable method of correlating the
luminosity of Cepheid stars with those of known types of ordinary stars is one of
the most important tools that astronomers have for ascertaining distances to
Line proximate galaxies. Fortunately, Cepheids are luminous enough to be observed
(5) in other galaxies, not just in our own, such that scientists have established a
benchmark for their true brightness. One first observes a Cepheid, notes the
time span for its luminance to vary, and plots that information on an already
established graph to derive its intrinsic luminosity. Comparing intrinsic
luminosity with apparent brightness allows one to calculate the star’s distance
(10) as long as the period-luminosity relation for the star in question is first corrected
for gravitational interference, parallax, and experimental error. Data gathered
by this process would suggest that the universe is expanding, but the method is
less reliable in the nether reaches of the universe, where the crucial evidence
for cosmic expansion would likely be spotted. [br] It can be inferred from the passage that the Cepheid variable method of estimating galactic distances would be likely to yield experimentally flawed results in which of the following circumstances?
选项
A、If the luminosity of ordinary stars being compared with that of a Cepheid star were affected by parallax.
B、If the apparent brightness of the Cepheid star being studied required an unusually long period of time to vary.
C、If the gravitational interference surrounding the Cepheid star being observed were more negligible than in most cases.
D、If the Cepheid star being studied existed on the periphery of the universe, at an extremely large distance from the observer.
E、If the Cepheid star being studied were in the same galaxy as the observer.
答案
D
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3353778.html
相关试题推荐
Claim:CountryX’sgovernmentloweredtariffbarriersbecausedoingsoservedth
Theinterviewisanessentialpartofasuccessfulhiringprogrambecause,with
Becausedinosaurswerereptiles,scientistsonceassumedthat,likeallreptiles
Nineteenth-centuryartcriticsjudgedartbytherealismofitsmethodofrepres
Becauseyoungchildrendonotorganizetheirattentionorperceptionssystematic
Becausenaturalgasiscomposedmostlyofmethane,asimplehydrocarbon,vehicle
Someanalystspointoutthatbecausepeoplearebecomingaccustomedtoasteady
TheRorschzchtestisgainingnewrespectasadiagnostictoolbecauseittakes
Teratomasareunusualformsofcancerbecausetheyarecomposedoftissuessuch
Theattorneyturneddownthelawfirm’sofferofapositionbecauseshesuspecte
随机试题
A—plannedeconomyI—seller’smarketB—marketeconomyJ—buyer’smarketC—World
HelpYourselfthroughtheHardTimesEveryone,atsomepoint
由于内部筹集一般不产生筹资费用,所以内部筹资的资本成本最低。()
图示结构两个状态中的反力互等,r12=r21,r12和r21的量纲为: A.
A.3.03A,45.45A B.45.45A,3.03A C.4.29A,
上述气的作用,可维持体温相对恒定的是A.推动作用 B.温煦作用
下列各项,不属于水停证临床表现的是()A.水肿按之凹陷不易起 B.小
按照《证券公司监督管理条例》的要求,证券公司要建立完备的内部控制体系。证券公司以
(2017年真题)由于被迫执行指令而违法违规的期货从业人员,依法履行了报告义务的
招标文件应规定一个适当的投标有效期。投标有效期的起始时间是()A:提交投标文件之
最新回复
(
0
)