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
18
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 passage, which of the following is true about the way stars usually form?
选项
A、They tend to overlap as they appear.
B、They tend to result from the residual matter of supernovas.
C、They tend to generate in sudden irregular fits.
D、They tend to destroy their progenitor clouds.
E、They tend to form away from gas coronas.
答案
C
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3968490.html
相关试题推荐
Thatlargeregionsofthegalaxycanbeinfluencedbytheformation
Thatlargeregionsofthegalaxycanbeinfluencedbytheformation
Thatlargeregionsofthegalaxycanbeinfluencedbytheformation
Diseaseisafluidconceptinfluencedbysocietalandculturalatti
Diseaseisafluidconceptinfluencedbysocietalandculturalatti
Diseaseisafluidconceptinfluencedbysocietalandculturalatti
BeforeGibson,populardiscoursesurroundingtheInformationAgeof
BeforeGibson,populardiscoursesurroundingtheInformationAgeof
BeforeGibson,populardiscoursesurroundingtheInformationAgeof
Mildelectriccurrenthadbeenthoughtto______overactivebrainregionsthatcau
随机试题
Astheplanecircledovertheairport,everyonesensedthatsomethingwaswr
ListL:4,5,6,7,7,8,xListLconsistsof7numbers.Whichofthefollowing
PoorpeoplehaveI.Q.’ssignificantlylowerthanthoseofrichpeople,andt
膜迷路包括:A.膜半规管 B.以上都不是 C.球囊 D.椭圆囊 E.膜蜗
钢筋拉伸试验一般应在(10-35)℃环境温度条件下进行。
涎腺多形性腺瘤之所以称为混合瘤是因为()A.肿瘤内既有涎腺上皮,又有
()是指以生存为给付保险金条件,按约定分期给付生存保险金,且分期给付生存
《隔离开关分合闸位置“双确认”改造技术规范》中视频监控应具有对一次主设备状态实时
合约基准价的高低是根据提出需求的一方的需求来确定的。( )
新拌砂浆的流动性用()表示,保水性用()表示。A.沉入度、分层度 B.坍落度、
最新回复
(
0
)