首页
登录
职称英语
The earliest known galaxies in the universe, which formed during the universe
The earliest known galaxies in the universe, which formed during the universe
游客
2024-06-03
2
管理
问题
The earliest known galaxies in the universe, which formed during the universe’s "dark age" nearly 13 billion years ago, have been spied by two teams of astronomers.
The discoveries, reported separately in this week’s issue of the journal Nature. suggest that galaxies were forming just 700 million years after the birth of the universe.
Theory holds that the universe formed 13.7 billion years ago when an extremely dense concentration of mass rapidly expended in an event known as the big bang.
The universe has been expanding ever since, so astronomers are able to age galaxies by computing how much. the wavelength of their light has stretched—or redshifted—as the expansion takes the galaxies farther from Earth. The redder the light is, the older and more distant the galaxy is.
The detection of such ancient galaxies adds intrigue (神秘色彩) to theories of how the very first galaxies formed, according to astronomers.
Were there many large, young galaxies in the early universe that are obscured from astronomers’ view by abundant gases absorbing their light? Or were galaxies rare and small way back then, as a prevailing theory suggests, and later clumped together to form larger galaxies such as the Milky Way?
"We believe that we need both these processes to explain what we see." Masanori lye, a professor at the National Astronomical Observatory of Japan. said in an email.
The galaxy, called IOK-1, formed about 750 million years after the big bang--60 million years closer to the event than the previous record holder.
Given the number of galaxies found during a later epoch about 810 million years ago, the researchers had expected to find as many as six galaxies like IOK-1 But the comparative rarity(稀有) of objects like IOK-l means that the universe must have changed significantly over the 60 million years that separate the two epochs, the team suggests.
lye and colleagues believe that they are witnessing the last phase of a process known as reionization(再次电离).
According to Iye, about 380,000 years after the fiery hot big bang, the universe cooled so much that protons and electrons recombined to form neutral hydrogen. This is known as the beginning of the dark age of the universe, because neutral hydrogen absorbs the light from stars.
As more galaxies started to form about 300 million years later, the hot stars heated the intergalactic (银河间的) medium and gradually reionized the neutral hydrogen back m protons and electrons. The ionized hydrogen then became more transparent, allowing the galaxies’ light to pass through
lye said the new results support the idea that neutral hydrogen was still abundant 750 million years after the big bang, blocking even older galaxies from view. "We are starting to see the last phase of cosmic reionization, or the dawn of the cosmic dark age," he said.
lye added that the discovery also supports the "hierarchical" theory of galaxy formation, which suggests that big, bright galaxies formed as smaller galaxies collided and merged. "The epoch we have probed is yet in this critical stage," he said. [br] According to the discoveries of the astronomers, when did galaxies form?
选项
答案
Just 700 million years after the birth of the universe.
解析
根据题干中的关键词discoveries和form定位到文章第二段,可知发现表明,星系形成于宇宙诞生七千万年以后,再结合上一段可知,这些发现是天文学家得出的。
转载请注明原文地址:https://tihaiku.com/zcyy/3618391.html
相关试题推荐
Theearliestknowngalaxiesintheuniverse,whichformedduringtheuniverse
Theearliestknowngalaxiesintheuniverse,whichformedduringtheuniverse
MarkwasastudentatPekingUniversityfrom1996~2000,during______(在这段时间里,他工
Theoriginsofbottledwatercanbe【B1】______backtotheearliest【B2】______
Theoriginsofbottledwatercanbe【B1】______backtotheearliest【B2】______
Theoriginsofbottledwatercanbe【B1】______backtotheearliest【B2】______
Theoriginsofbottledwatercanbe【B1】______backtotheearliest【B2】______
Theoriginsofbottledwatercanbe【B1】______backtotheearliest【B2】______
Theoriginsofbottledwatercanbe【B1】______backtotheearliest【B2】______
[originaltext]Duringthepastdecade,therehasbeenamultifoldincreasei
随机试题
TrappedthousandsofyearsagoinAntarcticice,recentlydiscoveredairbubbles
[originaltext]W:Dan,didyouwanttoseeme?M:Oh,yes,Sue,pleasesitdown.
Thefoodweeatseemstohavesignificanteffectsonourhealth.Althoughs
下列关于防眩设施的作用,说法正确的是()。A.指示道路线形轮廓 B.防止
铝酸盐水泥()与硅酸盐水泥混用。A.可以 B.不可以 C.在干燥条件下可
起重机械应保持经常性调试,以保证部件或器件的功能正确,下列不属于经常调试项目的是
幼儿看见天上的云彩,说是“有个小孩在骑大马”,这是一种( )。A、注意 B、
迅龙公司是一家互联网科技公司,最近开发出一款市场中还未出现过类似功能的APP。由
根据物权法律制度的规定,下列关于建设用地使用权的表述中,说法正确的有()。
女性,45岁,8个月来双侧掌指和指间关节肿痛伴晨僵,饮食正常,下肢不肿,X线
最新回复
(
0
)