New exoplanet discovery sparks hope of hidden 'Tatooines'

A new discovery of a faraway planet, published today in the journal Nature Astronomy, is bringing more science to what was once the realm of science fiction.

The new exoplanet, TOI-1338/BEBOP-1c, is a gas giant 65 times the size of Earth and more than 1,300 light years away in a binary star system — where two suns revolve around each other. 

For some, it might recall a powerful scene from the original Star Wars movie — Luke Skywalker staring at the horizon, pining for a greater destiny than on the dustball of Tatooine, as the aptly named John Williams theme Binary Sunset plays in the background. 

While the fictional Tatooine was alone, BEBOP-1c is the second planet discovered in the real TOI-1338 system.

"It's quite an exciting discovery," said Matthew Standing, post-doctoral researcher at The Open University in Milton Keynes, England, and first author of the study. 

"It's only the second multi-planetary, circumbinary system and the first-ever circumbinary planet discovered with radial velocity."

Unpacking those terms is key to why experts think this could lay the groundwork for finding similar hidden exoplanets. But it requires understanding the chaos of such cosmic neighbourhoods and the methods used to detect exoplanets. 

In reality, binary star systems are far from unique. 

"Half of the stars that we look at in the night-time sky have a stellar companion," said Jason Rowe, Canada Research chair in exoplanet astrophysics and an assistant professor at Bishop's University in Sherbrooke, Que.

Finding evidence of multiple planets inside such systems is rarer. 

"It's not your typical, run-of-the-mill planetary system," remarked Rowe, who was not involved in the discovery. "It's studying the oddballs that sometimes create breakthroughs in our knowledge of how planetary systems form." 

It's not known in great detail how exactly planets form in systems like this. What is known: the gravitational dance of two stars can make for some inhospitable zones.

"Around binary stars there's a region where any planet's orbit would be unstable," said Standing, "So that means that planets have to exist slightly further out."

BEBOP-1c, highlighted in today's paper, is one of two planets discovered so far in that system. The other, TOI-1338 b, made headlines in 2020 after a summer intern at NASA helped discover it. Both are in stable orbits that are circumbinary, meaning they orbit around both stars.