Sat, Jun 13, 2009 - Page 2 News List

Research confirms star birth, magnetic fields link

BREAKTHROUGH A researcher at Academia Sinica was part of a team whose work provides a glimpse into how massive stars are formed from grains of dust

By Shelley Shan  /  STAFF REPORTER

An international team of astronomers has confirmed that interstellar magnetic fields are a crucial factor in the formation of massive stars. The research was published in the weekly journal Science yesterday.

Ramprasad Rao, a US scientist conducting research at the newly established Institute of Astronomy and Astrophysics (ASIAA) at Academia Sinica, joined a group of scientists from Spain, Italy and the US to monitor a hot molecular cloud named G31.41+0.31, the home of very young massive stars. This was done through the use of a Submillimeter Array (SMA) in Hawaii.

According to Academia Sinica, while massive stars comprise only 1 percent of the stellar population of the galaxy, they dominate the appearance and evolution of the interstellar medium composed of gas and dust grains. But how these massive stars were formed remained a mystery.

Molecular cloud G31.41+0.31 is located 23,000 light years from Earth in the Serpens constellation. Scientists found that the dust grains in this particular cloud are partially aligned with magnetic field lines.

“From the dust-polarized emission detected with the SMA, we derived the structures of the magnetic field that threads the cloud. We found that it has an hourglass shape, similar to what we found three years ago around a Sun-like stellar embryo,” said Spanish scientist Josep Miquel Girart, the team’s head scientist, who was quoted in a statement released by Academia Sinica yesterday.

“But G31.41+0.31 is 20 times larger, 200 times more massive and 100,000 times brighter,” he said.

The scientists concluded that the magnetic field “is the main agent controlling the collapse of the cloud.”

They said, however, that the research also introduced new questions, such as the exact details of the process of how the molecular clouds broke into different massive stars.

Astrophysicist Frank Shu (徐遐生) described the results as a “breakthrough” and said they would provide an important link to the study of star formation in other galaxies.

“[Through the research] We can then hope to venture out to the distant universe, which promises to connect the science of star formation to the science of galaxy formation,” Hsu said. “We are on the threshold of another exciting unification in science.”

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