Using a recently developed technique to detect magnetic fields inside stars, a group of astronomers¹ -- including Matteo Cantiello and Lars Bildsten from UC Santa Barbara's Kavli Institute for Theoretical Physics (KITP) -- has discovered that strong magnetic fields are very common in stars. The group's findings appear in the journal Nature. "We have applied² a novel theoretical idea that we developed just a few months ago to thousands of stars and the results are just extraordinary," said Cantiello, a specialist in stellar astrophysics at KITP.

 

Previously³, 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 component⁴.

 

"Such fields have simply been regarded as insignificant⁵ for our general understanding of stellar evolution," said lead author Dennis Stello, an astrophysicist at the University of Sydney in Australia. "Our result clearly shows this assumption needs to be revisited because we found that up to 60 percent of stars host strong fields."

 

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.

 

"The stellar core is the region where the star produces most of its energy through thermonuclear reactions," Cantiello explained. "So the field is likely to have important effects on how stars evolve since it can alter the physical processes that take place in the core."

 

Most stars -- like the sun -- are subject to continuous oscillations. "Their interior is essentially⁶ ringing like a bell," noted⁷ co-author Jim Fuller, a postdoctoral scholar from the California Institute of Technology in Pasadena. "And like a bell or a musical instrument, the sound produced reveals physical properties, such as size, temperature and what they are made of."

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