Eta Carinae
As possibly the galaxys most massive star, Eta Carinae is now engaging in some very unusual behaviour. Australian astronomers, being in the Southern Hemisphere , are able 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 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 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 . There has not been a supernova in our galaxy 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 ultravioletlaser that is brighter than that produced by the Sun. Lasers have been observed in other frequencies from a few stars.
31. Eta Carinae is now engaging in
A. some very common behaviour B. some very dull behaviour
C. some very frightening behaviour. D. some very strange behaviour
32. The word period in Paragraph 3 means the length of time
A. over which star vary in brightness
B. for which Eta carinaes brightening lasts.
C. Eta carinae takes to become a supernova.
D. it takes the laser from Eta carinae to travel to the earth.
33. Eta Carinae is hard to observe because
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.
34. Astronomers are particularly interested in Eta Carinae because
A. it is in its final stage. B. it is a supernova.
C. it exploded in 1987. D. it is brighter than the sun.
35. Which of the following statements about Eta Carinae is NOT true?
A. It will end up as a supernova.
B. It can be seen only through binoculars.
C. It is the only star that sends out an ultraviolet laser.
D. Its ultraviolet laser is brighter than that of the Sun.
Answers: 31. D 32. A 33. B 34. A 35. C
四级考试听力备考笔记(30)
四级考试听力备考笔记(33)
英语四级晨读100篇精华版065书籍(中英)
四六级考试备考听力课堂笔记(21)
四级考试听力备考笔记(8)
过关必读:2014年12月大学英语四级听力技巧(4)
四六级考试备考听力课堂笔记(20)
大学英语四六级晨读经典365夏日激情篇107
四级考试听力备考笔记(32)
四六级考试备考听力课堂笔记(10)
英语听写训练法及四六级听力备考要点
四级考试听力备考笔记(11)
四级考试听力备考笔记(63)
英语听力理解常见问题及对策
英语四级考试听力语段题10大解题原则
四级考试听力备考笔记(40)
四级考试听力备考笔记(39)
过关必读:2014年12月大学英语四级听力技巧(1)
四级考试听力备考笔记(29)
四级考试听力备考笔记(28)
四级考试听力备考笔记(37)
四级考试听力备考笔记(56)
四级考试听力备考笔记(43)
四六级考试备考听力课堂笔记(11)
四级考试听力备考笔记(22)
过关必读:2014年12月大学英语四级听力技巧(5)
四级考试听力备考笔记(51)
四级考试听力备考笔记(38)
英语四级晨读100篇精华版035个人隐私 (中英)
英语四级晨读100篇精华版075
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |