Scientists hunting for life beyond Earth have discovered more than 1,800 planets outside our solar system, or exoplanets, in recent years, but so far, no one has been able to confirm an exomoon. Now, physicists from UT Arlington believe following a trail of radio wave emissions may lead them to that discovery.
Their recent findings, published in the Aug. 10 issue of The Astrophysical Journal
, describe radio wave emissions that result from the interaction between Jupiter’s magnetic field and its moon Io. They suggest using detailed calculations about the Jupiter/Io dynamic to look for radio emissions that could indicate moons orbiting an exoplanet.
“This is a new way of looking at these things,” said Zdzislaw Musielak, professor of physics in the College of Science and co-author of the new paper. “We said, ‘What if this mechanism happens outside of our solar system?’ Then, we did the calculations and they show that actually there are some star systems that if they have moons, it could be discovered in this way.”
Joaquin Noyola, a Ph.D. graduate student in Musielak’s research group, is lead author on the new paper and Suman Satyal, a Ph.D. graduate student in the same group, is another co-author. It is titled “Detection of Exomoons Through Observation of Radio Emissions.”
The idea of life thriving on a moon has inspired science fiction, such as Star Wars’ furry Ewoks. Scientists even think some moons in our own Solar System - Saturn’s Enceladus and Jupiter’s Europa - are good candidates for supporting life based on their atmospheric composition, potential for water and distance from the sun.
The difficulty comes in trying to spot an exomoon using existing methods, Musielak said. NASA’s Kepler telescope, for example, measures changes in brightness from a star to identify transits, or passes, by an orbiting planet. Reliably isolating whether a moon is part of that transit hasn’t been possible, so far.
The UT Arlington team builds on earlier theories about using radio wave observations to discover exoplanets, but applies it in a new way. Their focus is on Io and its ionosphere, a charged upper atmosphere that is likely created by the moon’s extremely active volcanoes.
During its orbit, Io’s ionosphere interacts with Jupiter’s magnetosphere, a layer of charged plasma that protects the planet from radiation, to create a frictional current that causes radio wave emissions. These are called “Io-