Astronomers using the LOw Frequency Array (LOFAR), a large radio telescope network located mainly in the Netherlands, have detected circularly polarized bursty emission from the tau Boötis (τ Boötis) system.
An artist’s impression of the hot-Jupiter exoplanet tau Boötis b. Image credit: L. Calçada / ESO.
Tau Boötis is a binary stellar system approximately 51 light-years away in the constellation of Boötes.
It consists of a hot and young F-type star, tau Boötis A, and a smaller M3-type (red dwarf) star, tau Boötis B.
In 1996, a hot-Jupiter exoplanet was discovered orbiting the primary star tau Boötis A.
Named tau Boötis b, the alien world has a mass almost 6 times that of Jupiter and an orbital period of 3 days and 7.5 hours.
“We present one of the first hints of detecting an exoplanet in the radio realm,” said Dr. Jake Turner, an astronomer in the Department of Astronomy and Carl Sagan Institute at Cornell University and the Department of Astronomy at the University of Virginia.
“The signal is from the tau Boötes system, which contains a binary star and an exoplanet.”
“We make the case for an emission by the planet itself. From the strength and polarization of the radio signal and the planet’s magnetic field, it is compatible with theoretical predictions.”
“If confirmed through follow-up observations, this radio detection opens up a new window on exoplanets, giving us a novel way to examine alien worlds that are tens of light-years away,” said Professor Ray Jayawardhana, an astronomer in the Department of Astronomy and Carl Sagan Institute at Cornell University.
Using the LOFAR radio telescope, Dr. Turner, Professor Jayawardhana and their colleagues observed three planet-hosting systems: tau Boötis, 55 Cancri and Upsilon Andromedae.
Only the tau Boötes system exhibited a significant radio signature, a unique potential window on 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,” Dr. Turner said.
“The magnetic field of Earth-like exoplanets may contribute to their possible habitability by shielding their own atmospheres from solar wind and cosmic rays, and protecting the planet from atmospheric loss.”
“There remains some uncertainty that the detected radio signal is from the planet. The need for follow-up observations is critical,” he said.
The results were published today in the journal Astronomy & Astrophysics.
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J.D. Turner et al. The search for radio emission from the exoplanetary systems 55 Cancri, upsilon Andromedae, and tau Boötis using LOFAR beam-formed observations. A&A, in press; doi: 10.1051/0004-6361/201937201
