Using a recently developed technique to detect magnetic fields inside stars, a team of astronomers has discovered that these are very common in stars.

"We have applied a novel theoretical idea that we developed just a few months ago to thousands of stars and the results are just extraordinary," said one of the researchers Matteo Cantiello from University of California-Santa Barbara.

Previously, only a very small percentage of stars were known to have strong magnetic fields. Therefore, current scientific models of how stars evolve do not include magnetic fields as a fundamental component.

"Our result clearly shows this assumption needs to be revisited because we found that up to 60 percent of stars host strong fields," lead author Dennis Stello, astrophysicist at the University of Sydney in Australia said.

Until now, astronomers have been unable to detect these magnetic fields because such fields hide deep in the stellar interior, out of sight from conventional observation methods that measure only the surface properties of stars.

The research team turned to asteroseismology, a technique that probes beyond the stellar surface, to determine the presence of very strong magnetic fields near the stellar core.

Most stars -- like the sun -- are subject to continuous oscillations.
"Their interior is essentially ringing like a bell," co-author Jim Fuller from the California Institute of Technology in Pasadena, noted.

"And like a bell or a musical instrument, the sound produced reveals physical properties, such as size, temperature and what they are made of," Fuller pointed out.

The researchers used very precise data from NASA's Kepler space telescope to measure tiny brightness variations caused by the ringing sound inside thousands of stars.

They found that certain oscillation frequencies were missing in 60 percent of the stars due to suppression by strong magnetic fields in the stellar cores.
The findings appeared in the journal Nature.