首页
登录
职称英语
Lunar sight-seeing trips and orbiting space hotels are within reach, moon wal
Lunar sight-seeing trips and orbiting space hotels are within reach, moon wal
游客
2023-12-21
37
管理
问题
Lunar sight-seeing trips and orbiting space hotels are within reach, moon walking astronaut Edwin"Buzz" Aldrin said last week, but some who favor space tourism worried about its "giggle factor". Astronomers have known for years that a source of intense energy emissions lies at the center of the Milky Way Galaxy, obscured from view by vast clouds of dust and gas. In February, 1992, researchers at the Max Planck Institute in Garching, Germany, reported evidence that the mysterious energy source is a gigantic black hole.
Observations have shown that many strong energy sources lie at the heart of the Milky Way. One of them, called Sagittarius A, is thought to be the actual center of the Galaxy, the point about which the great spiral of stars rotates. Sagittarius A is a powerful emitter of radio waves and X-rays.
Astronomers have considered two possible explanations for the identity of Sagittarius A. They theorized that it is either a compact duster of normal stars or a super-massive black hole containing as much as a million or more suns. The German scientists reported that they found strong evidence in support of the black hole explanation.
The astronomers used a new telescope high in the Andes Mountains of Chile to obtain the sharpest images ever made of the region around Sagittarius A. The image shows that Sagittarius A is a single, small object rather than a duster of stars.
The researchers also found that a bubble of gas is expanding outward from Sagittarius A. This expanding gas is similar in temperate, density, and composition to the jets of gas that astronomers have observed flow hag away from the centers of many other galaxies. Such jets are thought to be generated by accretion disks surrounding enormous black holes. Accretion disks are vast, swirling masses of gas and dust that give off titanic amounts of energy as they are sucked into the black hole. The similarity between the jets emitted by some galaxies and the gas bubble surrounding Sagittarius A supports the idea that Sagittarius A is a super-massive black hole. [br] Sagittarius A is ______.
选项
A、clearly a super-massive black hole
B、a compact cluster of normal stars
C、a single, small subject
D、still an issue of controversy
答案
D
解析
文章第三段指出,天文学家对于Sagittarius A的身份提出了两种可能的解释,而综观全文可知,尽管他们发现了一些用来证明Sagittarius A是黑洞的证据,但这毕竟在整个科学界尚未形成定论,因此[D]为正确答案。
转载请注明原文地址:https://tihaiku.com/zcyy/3291636.html
相关试题推荐
Mostearthquakesoccurwithintheupper15milesoftheearth’ssurface.But
Mostearthquakesoccurwithintheupper15milesoftheearth’ssurface.But
Mostearthquakesoccurwithintheupper15milesoftheearth’ssurface.But
Mostearthquakesoccurwithintheupper15milesoftheearth’ssurface.But
Lunarsight-seeingtripsandorbitingspacehotelsarewithinreach,moonwal
Lunarsight-seeingtripsandorbitingspacehotelsamwithinroach,moonwalk
Lunarsight-seeingtripsandorbitingspacehotelsamwithinroach,moonwalk
Lunarsight-seeingtripsandorbitingspacehotelsamwithinroach,moonwalk
TheFamilyThenandNow Thingswerenevereasywithinthefam
TheFamilyThenandNow Thingswerenevereasywithinthefam
随机试题
[originaltext]"Couldyouhearme?"StephenHawkingaskedinhisiconiccomp
DeafnessLatestSituationAbout16-mill
某药用植物具如下特征:草本,复叶,二体雄蕊,心皮1,果实为荚果,该植物可能属于A
根据行政、事业单位财务规则的规定,专用设备作为固定资产的单位价值标准是()。A
双组分路面标线涂料干膜厚度一般控制在()。A.0.4~2.5mm之间 B.0.
下列不属于基金销售机构人员从事的工作范围的是( )。A.分析基金走势 B.
下列哪种药是抗躁狂药A:地西泮 B:丙米嗪 C:氟西汀 D:丁螺环酮 E
图示结构中,各构件的自重不计,已知:力偶矩的大小m=60kN·m,其转向为顺时针
以下属于劳资冲突表现形式的有( )。A.请愿上访 B.示威、集会 C.怠工
目前采取的用乙烯为原料,通过氧化或氧氯化制乙醛,不需用汞做催化剂,彻底消除了汞害
最新回复
(
0
)