Artist concept of the first stars. Credit: Harvard Smithsonian CfA
What were the first stars like that formed shortly after the Big Bang? We don't know much about the conditions of the early universe 13 billion years ago, but a new computer simulation provides the most detailed picture yet of the first stars and how they came into existence. The composition of the early universe was quite different from that of today, said Dr. Naoki Yoshida, Nagoya University in Nagoya, Japan and Dr. Lars Hernquist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA. An article that will be published to the August 1 journal Science describes their findings from the computer model that simulates the early days of the universe, the "cosmic dark ages," where the physics governing the universe were somewhat simpler. The astronomers believe small, simple protostars formed, which eventually became massive, but short-lived stars.
According to their simulations, 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 the early stages of a star called a protostar. With a mass of just one percent of our Sun, 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. These stars would have been up to one hundred times as massive as our Sun and would have burned for no more than one million years. "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 in the origins of life and planets," said Hernquist.
"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."
The goal of their research is to be able to figure out how the primordial stars formed, as well as predicting the mass and properties of the first stars of the universe. The researchers hope to eventually extend this simulation to the point of nuclear reaction initiation – when a stellar object becomes a true star. But that's the point where the physics becomes much more complicated, and the researchers say they'll need more computational resources to simulate that process.
According to their simulations, 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 the early stages of a star called a protostar. With a mass of just one percent of our Sun, 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. These stars would have been up to one hundred times as massive as our Sun and would have burned for no more than one million years. "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 in the origins of life and planets," said Hernquist.
"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."
The goal of their research is to be able to figure out how the primordial stars formed, as well as predicting the mass and properties of the first stars of the universe. The researchers hope to eventually extend this simulation to the point of nuclear reaction initiation – when a stellar object becomes a true star. But that's the point where the physics becomes much more complicated, and the researchers say they'll need more computational resources to simulate that process.
