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Web address:
http://www.sciencedaily.com/releases/2008/07/
080731143329.htm
How The First Stars In The Universe Came Into Existence
The first primordial stars began as tiny seeds that grew rapidly into
stars one hundred times the mass of our own Sun. Seen here in this
artist's impression, swirling clouds of hydrogen and helium gasses are
illuminated by the first starlight to shine in the Universe. In the
lower portion of the artwork, a supernova explodes, ejecting heavier
elements that will someday be incorporated into new stars and planets.
(Credit: Image courtesy of David A. Aguilar (CfA) via Science/AAAS)
ScienceDaily (Aug. 1, 2008) Researchers believe that our universe
began with the Big Bang 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 simulation now
offers the most detailed picture yet of how these first stars in the
universe came into existence, researchers say.
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
-- the early stage of a massive primordial 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 question 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 mysterious "dark matter" of the
universe after the Big Bang in order to form this early stage of a
star -- a protostar with a mass of just one percent of our sun. The
simulation reveals how pre-stellar 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 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 Hernquist, 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 when you think about
it, 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 simulation to the point of nuclear reaction
initiation -- 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."
Journal reference:
1. Yoshida et al. Protostar Formation in the Early Universe.
Science, August 1, 2008
Adapted from materials provided by American Association for the
Advancement of Science.
Need to cite this story in your essay, paper, or report? Use one of
the following formats:
APA
MLA
American Association for the Advancement of Science (2008, August 1).
How The First Stars In The Universe Came Into Existence. ScienceDaily.
Retrieved August 1, 2008, from http://www.sciencedaily.com
/releases/2008/07/080731143329.htm
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