Researchers have looked at what's inside stars, discovering clues that help understand their evolution.
Astronomers are well aware of the existence of protective magnetic fields on the external structures of stars. Now researchers are able to look inside dozens of giant red stars, evolved versions of the sun that are near the end stages of a star's life cycle. Their findings showed that these magnetic fields are present even to the very cores of these stars.
By examining stars' interior magnetic fields, the researchers said that astronomers will be able to understand how stars move, evolve, and eventually die.
A team of scientists from the University of California-Santa Barbara, the California Institute of Technology and the University of Sydney, were able to do this using an astronomy technique called astroseismology to calculate the magnetic field strengths in the cores of the red giants based on the interpretation of sent frequencies.
"(It is similar to the way) medical ultrasound uses sound waves to image the interior of the human body," explained Jim Fuller, study co-author and a CalTech postdoctoral researcher, who said that astroseismology made use of sound waves generated by turbulences found stars' external surface.
Researchers added that the technique was not used on the sun and other stars because their cores were made of a primarily hydrogen-helium combination which lacked the density of the oxygen cores red giants possessed.
"We still don't know what the center of our own sun looks like," Fuller said.
Based on their findings, researchers discovered that stars also experience a so-called "magnetic greenhouse effect," deriving its name from a similar event seen on Earth: carbon dioxide waste trapping heat reflected by the sun. In this case, gravity waves are trapped in the star's core due to the intensity of the magentic fields that make up its core and surface.
This greenhouse effect possibly causes the dipole pattern on red giants, wherein one hemisphere is brighter than the other. The same effect was also observed by a study made by NASA in 2013.
Astronomers are delighted by the team's findings because of its implications in the study of the evolution and eventual death of stars.
"This is exciting, as internal magnetic fields play an important role for the evolution and ultimate fate of stars," said Sterl Phinney, CalTech's executive officer for astronomy.
