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
52
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.
Eta Carinae is hard to observe because
选项
A it is too far away.
B there is too much dust and gas around it.
C the binoculars are not powerful enough.
D it does not send out infrared light
答案
B
解析
转载请注明原文地址:https://ti.zuoweng.com/ti/vbsQKKKQ
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...
SoMany“Earths” TheMilkyWay(银河)containsbillionsofEarth-sizedplanets...
EtaCarinae Aspossiblythegalaxy’s(银河)mostmassivestar,EtaCarinaeis...
随机试题
男,18岁,踢足球时不慎摔倒后半小时就诊,查见上唇软组织挫裂伤,摇动任何一个牙,
远志常采用的炮制方法是 A、豆腐煮 B、姜汤煮 C、水煮 D、甘草
临床实验室检查主要内容有()。
基底下地质条件完全相同的两个条形基础,按《建筑地基基础设计规范》(GB5000
股份有限公司增加或减少资本,应当修改公司章程,须经出席股东大会的股东所持表决权的
从所给的四个选项中,选择最合适的一个填入问号处,使之呈现一定的规律性。
“生旦净末丑”是京剧的行当,其中“净”是( )。 A.男角 B.女角 C.儿童 D.男女均可
()的目标顾客为中高档消费者和追求时尚的年轻人。A:百货商店B:超级市场C:专业店D:专卖店
关于现值和终值,下列说法错误的是()。A.随着复利计算频率的增加,实际利率增加,现金流量的现值增加B.期限越长,利率越高,终值就越大C.货币投资的时间越早,
以下有关定期寿险的说法中错误的是()。A.定期寿险又称“定期生存保险”,是人寿险中最简单的一种B.如果定期寿险的被保险人在保险期满时仍然生存,则保险合同即行终