No Longer the Stuff of Sci-Fi: Astronomers Discover Planet Orbiting Twin Stars Through Revived Method

A team of ground-breaking astronomers has successfully deployed an old technique, known as the radial velocities method, to locate a unique circumbinary planet, a celestial body that orbits two stars. Along with this discovery, a second planet was unearthed orbiting the same pair of stars, making this only the second known instance of a multi-planet circumbinary system.

This international team of scientists is the inaugural group to employ the traditional radial velocities technique in unearthing a circumbinary planet – a type of planet that orbits dual stars.

In a fortunate turn of events, the team also detected a second planet revolving around the same binary stars, marking only the second known multi-planet circumbinary system. The research findings were made public on June 12 in the esteemed journal, Nature Astronomy.

Circumbinary planets, once confined to the realm of science fiction, are now recognized as more prevalent, thanks to data obtained from NASA’s Kepler mission. Astronomers have realized that star systems consisting of multiple stars are more widespread than previously believed. Although not all of these may have accompanying planets, approximately half the stars we see are part of binary, trinary, or even quadruple systems. The remaining half, like our sun, are single stars. Despite their abundance, the knowledge surrounding planets orbiting these multiple star systems is still relatively scant.

“As the planet orbits two stars, detection becomes slightly more challenging because both its stars are in motion through space,” explained David Martin, one of the study’s authors and a NASA Sagan Fellow in astronomy at The Ohio State University. “So, the ways we identify these stars’ exoplanets and the mechanisms of their formation are distinct.”

The newly identified system has been designated TOI-1338/BEBOP-1, named after the Binaries Escorted by Orbiting Planets project, initiated by the team to augment the tally of known circumbinary planets. This system is only the second binary star system known to house multiple planets. A total of just 12 circumbinary planet systems have ever been discovered.

The centerpiece of their discovery is a massive gas giant, which completes its orbital period around the two stars in 215 days.

But what makes this discovery stand out, according to Martin, is the technique employed to locate the planet. Among over 5,000 worlds that astronomers have discovered since the first exoplanet was detected in 1995, most have been found using the transit method. This method, which involves measuring the dip in a star’s brightness when a planet crosses between it and an observer on Earth, is generally considered the most effective way to ascertain the existence of other worlds.

In this research, however, the scientists are the first to report the detection of a known circumbinary planet using solely the radial velocities method. This technique measures the gravitational shifts exerted on host stars by their planets over time. It’s the same method that led to the discovery of the 1995 exoplanet, now known as Dimidium.

“While radial velocities were previously employed with relative ease to locate planets around single stars, this technique had not been successfully adapted for binary systems,” explained Martin.

Martin elaborated that while radial velocities are proficient at locating planets around single stars, they’ve historically struggled with binaries due to multiple sets of stellar spectra. However, by focusing on binaries where one star significantly outshines the other, the BEBOP program could help locate many more, he suggested.

Prior research indicated that radial velocities could be used to locate a known planetary system like Kepler-16, but this study pushes that work forward by discovering an entirely new planet.

This discovery may also hold promise for scientists

Frequently Asked Questions (FAQs) about Circumbinary Planet Discovery

More about Circumbinary Planet Discovery

• NASA’s Kepler mission
• James Webb Space Telescope
• The Radial Velocity Method for finding Exoplanets
• Binaries Escorted by Orbiting Planets (BEBOP) project
• European Southern Observatory (ESO)