The heavenly task of building a star is now thought to be much like any other: it takes longer to accomplish than expected.
A team of scientists reached this conclusion after studying clouds of gas and dust in the sky that serve as stellar incubators.
"Our observations indicate that we need to drastically revise our ideas about the very early stages of star formation," said Claire Chandler, an astronomer at the National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico.
To get a new perspective on the birth of stars, Chandler and the other scientists studied the clouds with a new light. The team observed the submillimeter radiation emitted from the dust and gas of protostars which had only been observed in optical and infrared radiation in the past. (Submilimeter radiation is more energetic than radio waves, but less energetic than infrared.) The scienitific team used SCUBA, a submillimeter camera at the James Clerk Maxwell Telescope in Hawaii.
in the scientific journal, Nature, that allowed them to examine these early stars by focusing telescopes on light from bright stars that were located behind the veiling clouds of gas and dust. But now, by studying these protostars in the submillimeter wavelength, many more of them are now known to exist. In turn this prevelence changes the idea of how long this stage in star development lasts.
Earlier studies had indicated that these early stars were about one-tenth as common as those visible to either infrared or optical telescopes, but the team found almost an equal number of both types.
Because both the veiled and visible stars are present in equal numbers, the scientists concluded, then the different stages of a star's life must last an equal amount of time. Roughly 200,000 years each, said Chandler.
The scientists also concluded that star development is heavily dependent on a triggering event to get started. One such event might be a nearby exploding star that sends shock waves through space, which would then cause gas clouds to collapse.
Another challenge to traditional wisdom about the early stages of star formation came in the team's analysis of gas clouds that have not yet begun collapse into stars. The astronomers found that starless cores probably last for only a short period.
"This means that, contrary to what we thought before, you don't need strong magnetic fields to hold these things up against gravitational collapse, because they don't last that long," Chandler said.
The study indicates that further study of star birth, formation, and death, as well as the role of magnetic fields in the life of a star, may need revision.
Chandler worked in partnership with John Richer and Anja Visser from the Mullard Radio Astronomy Observatory in the United Kingdom, and presented their results at the American Astronomical Society's meeting today in Washington, D.C..
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