Seeing Tau Boötis b in a New Light - Radio Waves
By: James Maynard
Tags: Space, Physics, Exoplanets, Astrophysics, Science

Tau Boötis b is seen radiating radio waves, providing astronomers with their first hints ever of a magnetic field surrounding an exoplanet.

The exoplanet Tau Boötis b is seen emitting radio waves, much like those seen around Jupiter in our own solar system. Image credit: The Cosmic Companion / Created in Universe Sandbox

Far from Earth, within the Tau Boötes planetary system, a massive exoplanet orbiting a pair of parent stars shines brightly in radio waves. These signals show the first hints of magnetic fields around worlds in other solar systems, and may offer astronomers a new way to explore alien worlds spread throughout the galaxy.

Radio waves emitted by this distant planet, recently been observed by astronomers at Cornell University, likely marks the first time radio waves have ever been seen coming from a planet outside our Solar System.

“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,” Jake D. Turner, postdoctoral researcher at Cornell University, said.

Join us on Astronomy News with The Cosmic Companion on January 5, 2021, when we will be joined by Dr. Jake Turner from Cornell University, discussing this fascinating study.

LOCLOSE and Yet LOFAR

The LOFAR network in the Netherlands offers a unique design in radio telescopes. Image credit: LOFAR / ASTRON

The Low Frequency Array (LOFAR), a radio telescope network based in the Netherlands, was utilized in an effort examining several exoplanets in our galactic neighborhood. This instrument is the largest telescope capable of seeing astronomical targets at the lowest frequencies visible from Earth.

Their targets included this hot Jupiter — a massive exoplanet orbiting close to its sun, as well as planets in the constellations Cancer and Andromeda.

The team began their search by examining radio emissions from Jupiter. These signals were then modeled, revealing how a similar signal in another star system would look from Earth.

Using this as a template, the team began their search of three planetary systems sitting 40 to 100 light years from Earth. Following roughly 100 hours of observations, one planet in the Tau Boötes system, 51 light years from Earth, was seen shining in radio waves.

The Tau Boötes solar system contains a pair of stars — a young, hot F-type star, and its companion, a cool red dwarf. These binary stars are accompanied by a massive hot Jupiter, racing around this system once every 80 hours.

There’s Something Attractive About Magnetic Fields…

An artist’s impression of the magnetic field surrounding Tau Boötes b. Image credit: Jack Madden / Cornell University

This finding — the first hint of a magnetic field around a world in an alien star system — could provide researchers with a new means to study exoplanets.

Within solar wind streaming from our own star, charged particles racing toward Earth bend, changing speeds as they encounter the magnetic field of our planet. This change in velocity can produce “squeaks” in radio data, sounding like bizarre alien birds.

“The atmosphere is thin and cold

The yellow sun is getting old

The ozone overflows with radio waves…”

Radio Waves, Roger Waters

Researchers believe that protons and electrons being warped in their path past Tau Boötis b could produce the signal seen by the astronomers. Measurements show the magnetic field of this world is likely between five to 11 Gauss, roughly as powerful as the magnetic field surrounding Jupiter.

However, by the time it reaches Earth, this signal is weak, so there remains uncertainty about whether or not this signal comes from an exoplanet. Solar flares might, instead, be responsible for the radio waves seen coming from the exoplanet, researchers caution.

Examination of radio waves around exoplanets could offer insights into the geology, as well as the atmosphere, of distant worlds. Researchers might also gain knowledge concerning interactions between planets and stars by examining the magnetic field surrounding these alien worlds.

A look at the theory how LOFAR was used to the find radio waves emanating from a massive world in a distant stellar system centered around a pair of suns. Video credit: Cornell University

A major challenge facing astronomers attempting to see radio waves from exoplanets is attempting to see through all the radiation surrounding Earth and our Sun.

“The detection of radio emissions from exoplanets will open up a vibrant new research field. Observing planetary auroral radio emission is the most promising method to detect exoplanetary magnetic fields, the knowledge of which will provide valuable insights into the planet’s interior structure, atmospheric escape, and habitability,” researchers wrote in Astronomy and Astrophysics.

Here on Earth, the magnetic field of our planet protects life from the solar wind. Image credit: Screenshot from NASA / Cornell University video

Life on Earth is protected by from solar radiation by the magnetic field surrounding our planet. Similar fields around exoplanets might also protect life on other worlds as well, researchers speculate.

“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,” Turner said.

Further studies will examine this target, and others like it, in greater detail. Soon, future studies like this one will become a new tool in the hands of astronomers, allowing them to better understand alien worlds orbiting distant stars.