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共用题干 第一篇How the First Stars in the Univ

恬恬2019-12-17  73
问题 共用题干第一篇

How the First Stars in the Universe Came into Existence

Researchers believe that our universe began with the Big Bang（宇宙大爆炸）about 13 billion years
ago,and that soon after that event,matter began to form as small dust grains and gases.How the first stars
formed from this dust and gas has been a burning question for years,but a state-of-the-art computer simula-
tion now offers the most detailed picture yet of how these first stars in the universe came into existence.
The composition of the early universe was quite different from that of today,and the physics that
governed the early universe were also somewhat simpler. Dr. Naoki Yoshida and colleagues in Japan and the
U.S.incorporated these conditions of the early universe,sometimes referred to as the"cosmic dark ages",to
simulate the formation of an astronomical object that would eventually shine its light into this darkness.
The result is a detailed description of the formation of a protostar（原恒星）一the early stage of a mas-
sive primordial（原始的）star of our universe , and the researchers ' computer simulation , which has been
called a"cosmic Rosetta Stone"sets the bar for further investigation into the star formation process.The ques-
tion of how the first stars evolved is so important because their formations and eventual explosions provided
the seeds for subsequent stars to come into being.
According to their simulation,gravity acted on minute density variations in matter,gases,and the myste-
riou;"dark matter"of the universe after the Big Bang in order to form this early stage of a star一a protostar
with a mass of just one percent of our sun. The simulation reveals how pre-stellar（前恒星的）gases would
have actually evolved under the simpler physics of the early universe to form this protostar.
Dr. Yoshida's simulation also shows that the protostar would likely evolve into a massive star capable of
synthesizing（合成）heavy elements,not just in later generations of stars,but soon after the Big Bang.
"This general picture of star formation,and the ability to compare how stellar objects form in different
time periods and regions of the universe,will eventually allow investigation into the origins of life and
planets,"said Lars Herriquist,a professor of Astronomy at Harvard University and a co-author of this latest
report."The abundance of elements in the universe has increased as stars have accumulated,"he says,"and
the formation and destruction of stars continues to spread these elements further across the universe.So all of
the elements in our bOdies originally formed from nuclear reactions in the centers of stars,long ago."
Their simulation of the birth of a protostar in the early universe signifies a key step toward the ambitious
goal of piecing together the formation of an entire primordial star and of predicting the mass and properties of
these first stars of the universe.More powerful computers,more physical data,and an even larger range will
be needed for further calculations and simulations,but these researchers hope to eventually extend this simu-
lation to the point of nuclear reaction initiation一when a stellar object becomes a true star.
"Dr. Yoshida has taken the study of primordial star formation to a new level with this simulation,but it
still gets us only to the halfway point towards our final goal.It is like laying the foundation of a skyscraper,"
said Volker Bromm,assistant professor of Astronomy at the University of Texas, Austin and the author of a
companion article."We must continue our studies in this area to understand how the initially tiny protostar
grows,layer by layer,to eventually form a massive star. But here,the physics become much more complicated
and even more computational resources are needed."
选项 According to the first two paragraphs,the early universe_______.A:was governed by simpler physicsB:got fewer stars shinning in itC:started over 13 billion years agoD:was composed in a way similar to that of today
答案A
解析根据第二段第一句可知，宇宙早期的物理现象比较简单。 根据第一段最后一句可知，现在一种先进的电脑模拟系统可以提供宇宙中最初的星球 产生的最详细的图片。 根据第三段第一句可推断出“an astronomical object”指的是原恒星。 根据第四段第一句可知，原恒星演化成巨大的星体是在大爆炸之后而非大爆炸期间。 最后一段提及了A、C、D选项所述内容，而B只是手段，而非目的。
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