Astronomers have used a combination of telescopes, including the ESO Very Large Telescope, to observe a system that has six exoplanets. What’s interesting about the system is that five of the exoplanets are locked in a rare rhythm around the central star. Astronomers believe the system could provide important clues about how planets, including those in our solar system, form and evolve.
The star at the center is called TOI-178 and is about 200 light-years away in the constellation Sculptor. Scientists originally thought they had spotted a pair of exoplanets going around the star in the same orbit. Further, inspection revealed no planets orbiting a star at roughly the same distance but multiple planets in a special configuration.
Research confirmed that the system boasts six exoplanets and that all but the closest to the star are locked in a rhythmic dance as they orbit. The planets are in resonance, meaning there are patterns that repeat themselves as the planets go around the stars. Some planets align every few orbits.
In our solar system, a similar resonance is observed in the orbit of three of Jupiter’s moons, Io, Europa, and Ganymede. The five outer exoplanets of TOI-178 following a more complex chain of resonance, which is the longest discovered in a system of planets so far. Jupiter’s three moons have a 4:2:1 resonance, while the five outer planets of TOI-178 following 18:9:6:4:3 chain.
The second planet from the star completes 18 orbits, the third completes nine orbits, and so on. Initially, only five planets were discovered in the system. Following the resonance rhythm, researchers could calculate where an additional planet would be when they had the next opportunity to observe it. Researchers say the resonance shows that the system is well ordered and evolved gently since its birth.