首页
财务会计
医药卫生
金融经济
考公考编
外语考试
学历提升
职称考试
建筑工程
IT考试
其他
登录
职称考试
Eta Carinae As possibly the galaxy’s (银河)most massive star, Eta Carinae is...
Eta Carinae As possibly the galaxy’s (银河)most massive star, Eta Carinae is...
admin
2020-12-24
15
问题
Eta Carinae
As possibly the galaxy’s (银河)most massive star, Eta Carinae is now engaging in some very unusual behaviour. Australian astronomers, being in the Southern Hemisphere(半球),are at)le to observe it clearly.
In the 19th century, Eta Carinae was for a time the third brightest star in the sky. It has now become less bright so that binoculars ( 双筒望远镜)are needed to see it. “ It seems to be brightening and becoming less bright over a period of many years” ,said Dr Bob Duncan
from the Australia Telescope National Facility.
While it is not unusual for stars to vary in brightness, the period is usually much shorter. “ Since 1992 it has become four times brighter,and then last year it began to drop dramatically, he said.
The problem in observing Eta Carinae is that it has been surrounded by a cloud of gas and dust, making it hard to see the star directly. However, radio waves and infrared light (红外线)can pass through this cloud,so telescopes that receive these wavelengths can observe what is occurring.
Eta Carinae is of particular interest to astronomers because it seems to be in its death throes (剧痛). Being so large it will end up as a supernova (超新星). There has not been a supernova in our geilaxy since the invention of the telescope. While a 1987 explosion in a nearby galaxy gave astronomers plenty of valuable data, they are hungry for an even closer look.
Eta Carinae has other unique features, and is the only star known to produce an ultraviolet (紫外线)laser that is brighter than that produced by the Sun. Lasers have been observed in other frequencies from a few stars.
The word "period" in Paragraph 3 means the length of time
选项
A over which stars vary in brightness.
B for which Eta Carinae’s brightening lasts.
C Eta Carinae takes to become a supernova.
D it takes the laser from Eta Carinae to travel to the earth.
答案
A
解析
转载请注明原文地址:https://ti.zuoweng.com/ti/kbsQKKKQ
相关试题推荐
Thecourageousboyhasbeenthesubjectofmassivemediacoverage.A:extensiveB:
Exercisewillpossiblyprotectagainstheartattacks.A:usually B:roughlyC:prob
SoMany“Earths” TheMilkyWay(银河)containsbillionsofEarth-sizedplanet...
SoMany“Earths” TheMilkyWay(银河)containsbillionsofEarth-sizedplanet...
SoMany“Earths” TheMilkyWay(银河)containsbillionsofEarth-sizedplanet...
SoMany“Earths” TheMilkyWay(银河)containsbillionsofEarth-sizedplanets...
SoMany“Earths” TheMilkyWay(银河)containsbillionsofEarth-sizedplanets...
SoMany“Earths” TheMilkyWay(银河)containsbillionsofEarth-sizedplanets...
EtaCarinae Aspossiblythegalaxy’s(银河)mostmassivestar,EtaCarinaeis...
EtaCarinae Aspossiblythegalaxy’s(银河)mostmassivestar,EtaCarinaeis...
随机试题
关于债券的特征描述错误的是( )。 A、安全性是指债券持有人的收益相对固定,
与透平式压缩机相比,活塞式压缩机的特点有()。
材料不同的两根受扭圆轴,其直径和长度均相同,在扭矩相同的情况下,它们的最大剪应力
全口义齿的前牙要排列成浅覆拾、浅覆盖的原因是因为
男性,58岁,进行性贫血、消痩、乏力半年,有时右腹有隐痛,无腹泻。查体:贫血貌,右中腹可触及肿块,肠鸣音活跃。 该病人术前准备中最重要的护理措施是A.给予高
社会生产力发展水平和发展状况的主要标志是科学技术。()
患儿8岁。发热2天,伴咽痛、皮疹1天,查体:T38.7℃,咽部充血,草莓舌,面部潮红,躯干部可见细小鲜红色充血性皮疹,诊断为猩红热,治疗首选A:红霉素B:头孢
我国现行房地产经纪行业管理中,通过( )的建设,可以提升房地产经纪人的职业道德水平和专业水平能力,塑造良好的职业形象,提高行业的社会公信力。A.房地产经纪人员
下列关于劳动合同的说法,正确的是()。A.建立劳动关系而没有订立劳动合同的,应该在用工之日起3个月内签订劳动合同B.劳动合同一律采用书面形式C.非
人力资源管理发展的顺序是()。A.人事管理萌芽阶段→科学管理阶段→人际关系运动阶段→传统人事管理成熟阶段→人力资源管理阶段→战略性人力资源管理阶段B.人事管