Wednesday, August 6, 2008

Researchers Found Cosmic Rosetta Stone

According to Japanese and U.S researchers who spent years developing a complex computer simulation of what it was like after the Big Bang that formed the universe, the first cosmological object formed in the universe was a tiny protostar with a mass of about 1 percent of our sun.

According to Naoki Yoshida of Nagoya University in Japan, the protostar was surrounded by a giant mass of gas and it grew to 100 times the sun's mass over about 10,000 years. That is very rapid growth on a cosmic scale. Lars Hernquist, a Harvard astronomy professor, the first stars were very different from stars like the sun. The early stars were primarily hydrogen and helium, and were much more luminous and had a shorter life, while the sun is mostly hydrogen; it also contains carbon and oxygen.

The typical lifetime of these early stars was a million years or so, while a star like the sun can continue for 5 billion years. Because of their short lifespan, none of the first generation of stars is still around. However, according to Hernquist, we do see stars in our galaxy that have very different properties than our sun, and it is possible these are second-generation stars.

In the simulation, gravity acted on tiny variations of the density of matter, gases and the so-called "dark matter" of the universe after the Big Bang, forming the early stage of a star. That protostar would evolve into a massive star capable of synthesizing heavy elements, not just in later generations of stars, but soon after the Big Bang, according to the analysis.

Hernquist said that that general picture of star formation, and the ability to compare how stellar form objects in different periods and regions of the universe, will eventually allow investigation into the origins of life and planets. More, Hernquist said that the abundance of elements in the universe has increased as stars have accumulated, and the formation and destruction of stars continues to spread these elements further across the universe.

According to Volker Bromm, an assistant astronomy professor at the University of Texas, the study may prove to be a "Cosmic Rosetta stone". On the other hand, Bromm, who was not part of the research team, said in a commentary that the findings could help researchers finally unlock the problem of understanding star formation, much as the Rosetta stone led to the understanding of ancient Egyptian writing. He said that 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 toward our final goal. It is like laying the foundation of a skyscraper. Moreover, he added that we must continue our studies in this area to understand how the initially tiny protostar grows, layer by layer, to form a massive star. Ministry of Education, Culture, Science and Technology of Japan and the Mitsubishi Foundation was an organization that funded by the research.

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