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
2025-02-22
29
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:http://tihaiku.com/zcyy/3968491.html
相关试题推荐
Thatlargeregionsofthegalaxycanbeinfluencedbytheformation
Thatlargeregionsofthegalaxycanbeinfluencedbytheformation
Thatlargeregionsofthegalaxycanbeinfluencedbytheformation
Thatlargeregionsofthegalaxycanbeinfluencedbytheformation
Diseaseisafluidconceptinfluencedbysocietalandculturalatti
Diseaseisafluidconceptinfluencedbysocietalandculturalatti
BeforeGibson,populardiscoursesurroundingtheInformationAgeof
BeforeGibson,populardiscoursesurroundingtheInformationAgeof
SPLENDOR:A、foulnessB、corruptionC、avariceD、transformationE、sincerityA
Mildelectriccurrenthadbeenthoughtto______overactivebrainregionsthatcau
随机试题
Theyholdthatanyonewhoisinneedshouldnotbe______assistancefromallot
Today,Americanfilmmakersproducemovieswithfewrestraintsaboutviolence
[originaltext]W:(13)CouldyoupleasegivemeinformationonairfaresfromMiami
对质量缺陷的处理需要坚持的原则包括( )。A.监理工程师具有质量否决权 B.
下列关于在享受型社会保障层面,商业保险的作用理解不准确的是()。A:提供更多的保
Thechangeinthatvillagewasmiraculou
消防设施可研初设审查验收,变电站应装设火灾自动报警装置,火灾报警信号火灾报警装置
统计体制,是指国家组织管理政府统计工作的体系和制度。()
液体的()性质,与液体是否发生燃烧、燃烧速率高低密切相关。A.蒸气压 B.闪
理论上,当市场利率上升时,将导致()A.国债期货价格下跌 B.国债期货价
最新回复
(
0
)