Astronomers Discover Strong Magnetic Fields in Majority of Stars

Majority of stars have strong magnetic fields which is contrary to what has been previously thought

Astronomers have found that majority of the stars possess strong magnetic fields.
An international group of astronomers led by University of Sydney has discovered that powerful magnetic field is a quite common phenomenon in stars, not rare as it was previously thought.


Using observational data from NASA’s Kepler Space Telescope, researchers have drawn a conclusion that the stars more massive than sun have internal magnetic field up to 10 million times stronger than the Earth. The remarkable finding will help researchers understand the evolution of stars in a more detailed manner.
“This is tremendously exciting and totally unexpected. Because only 5-0 percent of stars were previously thought to host strong magnetic fields, current models of how stars evolve lack magnetic field as a fundamental ingredient. Such fields have simply been regarded insignificant for our general understanding of stellar evolution.” Dennis Stello, astrophysicist associate professor from University of Sydney and lead author of the study said.

“Our result clearly shows this assumption needs to be revisited.”
A separate previous research suggested that presence of strong magnetic field could be detected by measuring stellar oscillations or sound waves. Sound waves bounce back and forth in the interior of stars and make them ring like a “bell.”

For the latest research, astronomers used a new technique called asteroseismology for probing beneath the surface of the star and found that more than 700 red giants stars or dying stars have shown the traces of strong magnetic field while certain oscillation frequencies were missing in 60% of the stars as they were suppressed by strong magnetic fields in their stellar core. Intermediate mass stars showed less evidence of the presence of magnetic field while magnetic fields were totally absent in stars with the same mass as the sun.

“Because our sample is so big we have been able to dig deeper into the analysis and can conclude that strong magnetic fields are very common among stars that have masses of about 1.5-2.0 times that of the Sun.” Stello said.

“In the past we could only measure what happens on the surfaces of stars, with the results interpreted as showing magnetic fields were rare.”

The finding is significant because magnetic fields can change physical process taking place in stellar core and have an impact on its composition. It also affects internal rotation rates and tells how a star grows old.

The study has implications for understanding how stars were evolved and how magnetic fields were formed inside the stars and it will also help determine the ultimate fate of stars.

The study was published in journal Nature.