By monitoring the cosmos with an array of radio telescopes, an international team of scientists led by Cornell University has detected radio bursts emanating from the constellation Boötes. The signal could be the first radio emission collected from a planet beyond our solar system.
The team, led by Cornell postdoctoral researcher Jake D. Turner, Philippe Zarka of the Observatoire de Paris-Paris Sciences et Lettres University. and Jean-Mathias Griessmeier from the Université d’Orléans, has published their findings in the research section of the journal Astronomy & Astrophysics.
“We present one of the first indications of the detection of an exoplanet in the realm of radio waves,” said Turner. ‘The signal is from the Tau Boötes system, which contains a binary star and an exoplanet. We argue that it is an emission from the planet itself, based on the strength and polarization of the radio signal and the magnetic field of this world, which are compatible with theoretical predictions.
Co-authors include Turner’s postdoctoral advisor Ray Jayawardhana, Dean Harold Tanner of Cornell College of Arts and Sciences, and professor of astronomy.
“If confirmed through follow-up observations, this radio detection opens a new window on exoplanets, giving us a novel way to examine alien worlds that are tens of light-years away,” Jayawardhana said.
Using the Low Frequency Array (LOFAR), a radio telescope in the Netherlands, Turner and his colleagues discovered bursts of emission from a star system that is home to a so-called hot Jupiter, a gas giant planet that is very close to its own sun. The group also looked at other possible candidates for exoplanetary radio emissions in the 55 Cancri (in the constellation Cancer) and Upsilon Andromedae systems. Only the Tau Boötes exoplanet system — some 51 light-years distant — exhibited a significant radio signature, a unique potential window in the planet’s magnetic field.
Observing an exoplanet’s magnetic field helps astronomers decipher a planet’s interior and atmospheric properties, as well as the physics of star-planet interactions, said Turner, a fellow at Cornell’s Carl Sagan Institute.
The Earth’s magnetic field protects it from the dangers of the solar wind, keeping the planet habitable.
“The magnetic field of Earth-like exoplanets can contribute to their possible habitability, protecting their own atmospheres from solar wind and cosmic rays, and protecting the planet from atmospheric loss”, the astronomer explained.
With the help of our Jupiter
Two years ago, the same team of scientists examined Jupiter’s radio emission signature and scaled those emissions to mimic possible signatures from a distant giant-like exoplanet. Those results became the template for looking for radio emissions from exoplanets 40 to 100 light years away.
After carefully studying nearly 100 hours of radio observations, the researchers were able to find the expected signature of the hot Jupiter at Tau Boötes.
“We learned from our own Jupiter what this type of detection is like. We went looking for it and we found it, ” Turner concluded, whose team has already started a campaign using multiple radio telescopes to track the signal.