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How Star Formation Prevents Star Formation
By SPACE.com Staff
posted: 10:06 am ET
06 November 2002
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EMBARGOED for Researchers have developed a new computer simulation that may help explain why star formation in galaxies is not as fast as expected. Stars themselves appear to be the culprits. Much of the hydrogen and helium that fills the space between stars in the Milky Way and other galaxies is the same material as what was formed soon after the Big Bang. Despite billions of years of gravitational influence, that material has not condensed into stars, due to some type of energy input that is continuously mixing it up. Alexei Kritsuk and Michael Norman, both from the University of California, San Diego, believe that ultraviolet radiation from clusters of massive, bright stars accounts for some of the turbulence. Their simulation shows that as a cloud of gas collapses under gravity into stars, the radiation from the new stars scatters the leftover material. The cycle then repeats on a time scale of millions of years. These types of stars have been observed in the spiral arms of the Milky Way galaxy and are known to regularly emit heavy doses of ultraviolet radiation. The researchers also based their model on calculations published earlier this year by a group of astrophysicists led by Antonio Parravano, which found that large, bright stars undergo eruptions of ultraviolet radiation every 10 million years. Astronomers have suspected other potential sources of the turbulence, including exploding stars called supernovae and the winds given off by massive new stars that are not caused by radiation. One of the differences in their model, the UCSD scientists say, is that ultraviolet light has a farther reach than and perturbs more space than the mechanical effects of supernovae or stellar winds. It may not, however, account for all of turbulence seen, they say. Kritsuk and Norman performed their calculations using supercomputers at UCSD and at the University of Illinois at Urbana-Champaign. Their findings will be published in the Nov. 20 issue of Astrophysical Journal Letters. More Deep Space News | Astronotes
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