JAN 06, 2016 11:59 AM PST

Strong magnetic fields are hiding deep inside stars

Until recently astronomers thought only a small percentage of stars have strong magnetic fields, but a new way to probe deeper into their cores could completely overturn that idea.

“Such fields have simply been regarded as insignificant for our general understanding of stellar evolution,” says Dennis Stello, an astrophysicist at the University of Sydney. “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.
 
"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," says Matteo Cantiello.


To solve the problem, researchers 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,” says Matteo Cantiello from the Kavli Institute for Theoretical Physics at University of California, Santa Barbara. “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 essentially ringing like a bell,” explains coauthor Jim Fuller, a postdoctoral scholar from the California Institute of Technology. “And like a bell or a musical instrument, the sound produced reveals physical properties, such as size, temperature, and what they are made of.”

Like an odd-sounding trumpet

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.

“It’s like having a trumpet that doesn’t sound normal because something is hiding inside it, altering the sound it produces,” says Stello, lead author of the paper in Nature.

This magnetic suppression effect had previously been seen in only a few dozen stars. However, the new analysis of the full data set from Kepler revealed that this effect is prevalent in stars that are only slightly more massive than the sun.

According to Cantiello, such intermediate mass stars are hotter and more luminous, and their cores are stirred by convection.

“We believe that the magnetic field is created by this ‘boiling’ sequence and stored inside the star for the remaining evolutionary phase. Astrophysicists previously have suggested this but it was very speculative; now it seems clear that this is the case,” he says.

“This is a very important result that will enable scientists to test more directly current theories for how magnetic fields form and evolve in stellar interiors,” says study coauthor Lars Bildsten, who directs the Kavli Institute. “When a star dies, the presence of strong magnetic fields can have a profound impact, possibly resulting in some of the brightest explosions in the universe.”

This research could potentially lead to a better general understanding of stellar magnetic dynamos, including the one controlling the sun’s 11-year sunspot cycle, which is known to affect communication systems and cloud cover on Earth.

“So far, the study of stellar magnetic dynamos principally relied on computer simulations, which now can be tested using these new exciting observations,” says Fuller.

This article was originally published on futurity.org
About the Author
  • Futurity features the latest discoveries by scientists at top research universities in the US, UK, Canada, Europe, Asia, and Australia. The nonprofit site, which launched in 2009, is supported solely by its university partners (listed below) in an effort to share research news directly with the public.
You May Also Like
NOV 27, 2018
Chemistry & Physics
NOV 27, 2018
Unraveling the Secret Behind the Strength of Spider Web
You don't need to watch a Spider-Man movie to notice how tough a spider web can be. Made of fiber-based spider silk, the seemingly fragile structure ca...
DEC 13, 2018
Chemistry & Physics
DEC 13, 2018
Biochemical Antifreezes: How Do They Work?
How do fish survive in the Arctic ocean where the temperature is under zero degree Celsius most of the year? They rely on a class of polypeptides called th...
DEC 17, 2018
Chemistry & Physics
DEC 17, 2018
Are We Any Closer to Harnessing Fusion to Generate Electricity?
Electricity is essential to our everyday lives, but the way we generate electricity with the burning of fossil fuels isn’t particularly suitable for...
DEC 19, 2018
Space & Astronomy
DEC 19, 2018
This is One of the Coldest Known Places in the Universe
Discerning the coldest place in the universe is no easy task; after all, we don’t have an ultra-long thermometer that we can merely extend out to the...
JAN 29, 2019
Space & Astronomy
JAN 29, 2019
Scientists Think This Video Representation Might Explain AT2018cow, A.K.A. 'the Cow'
AT2018cow, also commonly referred to as the ‘the Cow,’ was an incredibly bright flash of light that astronomers discerned in their telescopes l...
FEB 04, 2019
Cell & Molecular Biology
FEB 04, 2019
Insight Into the Earliest Stages of Life on Earth
Scientists have been looking for the origins of life on earth for many years. One theory that has emerged involves a biological molecule called RNA....
Loading Comments...