In a new space research paper, scientists have detailed the potential discovery of a planet orbiting a triple-star system, the first of its kind to be documented so far. Multi-star systems are not that rare in the known universe. So far, scientists have documented at least nine circumbinary planets that are known to orbit around two stars in the same system, with some of them even having slightly eccentric orbit. And even though they’re not thought of being habitable due to their gaseous nature, the discovery was indeed remarkable.

NASA’s Transiting Exoplanet Survey Satellite (TESS) — which recently captured sound waves coming from a star — discovered TOI 1338 b, its first two-star system in 2020 that was located some 1,300 light-years away in the Pictor constellation. The two stars of the system are known to orbit each other every 15 days, while the planet’s orbital activity happens in the same plane as the stars, leaving the doors open for a regular eclipse event. However, scientists haven’t been able to spot a circumtriple system where a planet is bound by the gravitational pull of three stars in the same system.

That might change thanks to research by astronomers at the University of Nevada in Las Vegas. While studying the GW Ori triple star system using the Atacama Large Millimeter/submillimeter Array (ALMA) radio telescope array — the same system that recently led to the discovery of organic molecules in disks around five nearby stars — scientists discovered some misalignment between each protoplanetary disk of the system. Scientists first that thought that the anomaly might be caused due to the torque generated by the interaction between the three stars, but they were wrong. Instead, the models created by the team suggest that there is a large unseen planet in the triple-star system that is the reason behind breaks in the GW Ori circumtriple disk. The planet hasn’t been seen yet, but based on gravitational modeling that predicts its presence, this planet is going to be the first circumtriple planet discovered so far.


A Rare Triple-Star System Planet That Remains Unseen


Using telescope arrays, scientists recorded the orbit of each star in the GW Ori system for over 11 years and discovered that the orbits are not in the same plane. Instead, they are misaligned with each other, and with respect to the disk itself. ‘Disk-tearing effect’ of stars’ gravitational pull was originally thought to be the reason behind the anomaly, causing the disk to break into multiple rings. However, simulations run by the team revealed that gravitational pull can not cause the misalignment in the system, and there was something else at play here.

However, a planet — a large one, somewhat like Jupiter — is very much capable of carving a dust gap and breaking the disk. It is unclear if the planet being hypothesized is fully formed, or still in the process of formation. It is also possible that there is not just one, but multiple planets in this triple star system. Scientists are now awaiting more readings from the ALMA telescope to advance their research and hopefully, find direct evidence of this first-of-its-kind circumtriple planet and add more knowledge to the theory of planet formation in multi-star systems.