首页
登录
职称英语
That large regions of the galaxy can be influenced by the formation
That large regions of the galaxy can be influenced by the formation
游客
2024-01-11
41
管理
问题
That large regions of the galaxy can be influenced by the formation of
massive stars in a few localized regions requires that star formation somehow be
coordinated over long periods of time. The process commences with a single O-
Line type star or a cluster of such stars in a giant molecular cloud, around which
(5) stellar radiation, winds and explosions carve a modest cavity from of the
surrounding interstellar medium, concomitantly destroying the progenitor
cloud. Perchance this disturbance triggers star formation in a nearby cloud, and
so on, until the interstellar medium in this corner of the galaxy resembles Swiss
cheese, composed of what theorists have recently begun to refer to as bubbles,
(10) or superbubbles, one of the most exciting discoveries in astrophysics in years.
Within a hot bubble, the sun has revealed itself in x-rays emitted by highly
ionized trace ions such as oxygen and at some point in the process of its
formation, nearby bubbles commence to overlap, coalescing into a superbubble.
The energy from more and more O-type stars feeds this expanding superbubble
(15) until its natural buoyancy stretches it from the midplane up toward the halo,
forming a chimney-the superbubble thus becomes a pathway for hot interior
gas to spread into the upper reaches of the galactic atmosphere, producing a
widespread corona. Far from its source of energy, the coronal gas slowly starts
to cool and condense into clouds. Over cons, these clouds fall back to the
(20) galaxy’s mid-plane, completing the fountain-like cycle and replenishing the
galactic disk with cool clouds from which star formation begins anew.
Star formation often occurs in sporadic but intense bursts, but in the Milky
Way the competing feedback effects almost balance out, so that stars form at an
unhurried pace-just 10 per year on average, except in some galaxies where
(25) positive feedback has gained the upper hand. 20 million to 50 million years ago,
star formation in the central parts of M82 began running out of control. Our
galaxy, too, may have had sporadic bursts, and the way these starbursts occur,
and what turns them off must be tied to the complex relation between stars and
the tenuous atmosphere from which they precipitate.
(30) Progress will be made in this complicated subject as astronomers continue
to study how the medium is cycled through stars, through the different phases
of the medium, and between the disk and the halo. Observations of other
galaxies give astronomers a bird’ s-eye view of the interstellar goings-on, and
answer such a critical question as whether stars are really the main source of
(35) power for the interstellar medium. The loop above the Cassiopeia superbubble
looks uncomfortably similar to the prominences that arch above the surface of
the sun, prominences which owe much to the magnetic field in the solar
atmosphere, and scientists have begun to wonder if magnetic activity dominates
our galaxy’s atmosphere. [br] According to the explanation given in the passage, which of the following causes superbubbles to gradually assume the shape of a chimney?
选项
A、The gravitational attraction of supernovas adjacent to the region of the chimney’s formation
B、The effect of entropy on the relative abundance of hot interior gas within the superbubble
C、A chemical reaction involving ionized trace ions at the heart of the superbubble
D、A tendency toward coalescence in the gases that contribute to the formation of the superbubble
E、A natural buoyancy of the superbubble, which causes the chimney to stretch and become a gaseous conduit
答案
E
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3353929.html
相关试题推荐
Schoolsexpecttextbookstobeavaluablesourceofinformationforstudents.My
Theprimarypurposeofthepassageisto______[br]Theinformationinthepassa
Schoolsexpecttextbookstobeavaluablesourceofinformationforstudents
Schoolsexpecttextbookstobeavaluablesourceofinformationforstudents
Schoolsexpecttextbookstobeavaluablesourceofinformationforstudents
Schoolsexpecttextbookstobeavaluablesourceofinformationforstudents
Ditramaisafederationmadeupofthreeautonomousregions:Korva,MitroandGu
Lackinginformationaboutenergyuse,peopletendtooverestimatetheamountof
Manyofthemchiseledfromsolidrockcenturiesago,themountainousregionsof
Iftheproposedexpendituresforgatheringinformationabroadarereducedevenf
随机试题
______oftenItry,Icannotfindtheanswer.A、AlthoughB、WhateverC、AsD、However
Whatdidthewomanthinkofthenewwingofthemuseum?[originaltext]M:Hey!Ho
明清两朝(theMingandQingDynasties)是中国小说的繁荣时期。从思想和主题方面来说,这个时代的小说包含了传统文化的精神,充分显
在组织行为学中,把一个人对于自己在某种环境中应该有什么样的行为反应的认识称为(
包含8个成员的开发小组的沟通路径最多有()条。A.28 B.32 C.56
存放HiCN转化液的容器应为A.无色有机玻璃瓶 B.棕色玻璃瓶 C.白色塑料
下列选项哪个能与题干立体图形①、②、③组合成3×3×3的立方体图形? A.如上
“壮水之主,以制阳光”适用于A.实寒证 B.实热证 C.虚寒证 D.虚热证
2020年10月,张某到甲公司工作。2021年11月,甲公司与张某口
下列工程中,超出二级注册建造师(建筑工程)执业资格范围的是()。A.高度9
最新回复
(
0
)