New technique for finding habitable planets looks for evidence of magnetic fields

Planets with magnetic fields produce radio waves that could be detectable from Earth.
By Laurel Kornfeld | Nov 09, 2018
Exoplanets capable of hosting life likely have magnetic fields, which protect them from stellar radiation produced by their host stars and prevent their atmospheres from eroding into space.

University of Virginia graduate student Jake Turner is developing new techniques to find evidence of exoplanets having magnetic fields as a means of searching for potentially habitable worlds, which likely range from Earth-sized to 2.5 times the size of our planet.

Earth's strong magnetic field helps it hold on to its atmosphere, which is crucial to sustaining life. In contrast, Mars is believed to have once had a strong magnetic field that could have produced conditions favorable to the development of life, but later lost most of that magnetic field, leading its water to escape into space and leaving the planet uninhabitable.

"One of the most elusive goals in exoplanet science today is the detection of exoplanetary magnetic fields. Knowledge of the magnetic field of a planet is extremely important because it can help us determine what the interior of a planet might be, whether it could be rocky and have the potential to possess an atmosphere with water, conditions needed for life," Turner stated.

Planets that have magnetic fields produce radio emissions that could be detectable by radio telescopes on Earth even though they are very faint.

To distinguish radio waves emanating from planets from radio waves produced by background noise, Turner is using Europe's Low Frequency Array (LOFAR) to measure radio emissions coming from Jupiter.

He is also working on developing specialized radio telescope techniques to detect radio waves coming from distant exoplanets.

"If we can get a handle on how to find direct radio emissions from large exoplanets, we can then eventually use these same techniques to study Earth-sized planets and determine which ones have magnetic fields. These magnetized Earth-sized planets would then be possible candidates to investigate further, looking for biological signatures, such as water vapor, in a search for life. The goal is to determine up to what distance and with what strength radio emission from exoplanets can be seen using LOFAR," Turner said.

To be detectable from Earth, the radio signal of an exoplanet 65 light years away in a region known to host many exoplanets would have to be one million times stronger than the strongest signals coming from Jupiter, he added.

Turner is presenting his research, which was published in the journal Astronomy and Astrophysics, at the 232nd meeting of the American Astronomical Society (AAS) in Denver, Colorado.

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