A rare star system known as orbital resonance has led astronomers to discover six planets revolving around a single star in a complex geometric pattern. The researchers have assembled a picture of the stunning but intricate HD110067 system, which is situated 100 light-years away, using data from both NASA’s Transiting Exoplanet Survey Satellite (TESS) and the European Space Agency’s Characterising ExoPlanet Satellite (CHEOPS).
The system’s six planets orbit in a pattern where one completes three orbits and another completes two, one completes six orbits and another completes one, one completes four orbits and one completes three, and so on. Each of the six planets resonates with the planets next to it, forming what is known as a “resonant chain.”
The system is so unusual because of this chain of resonances. Resonances and multiplanet systems are not uncommon among the more than 5,000 exoplanets that have been found orbiting stars other than our sun. But finding systems where the resonances stretch over such a long chain of six planets is incredibly uncommon, according to a statement from one of the researchers, Hugh Osborn of the University of Bern.
These planets are all sub-Neptunes, which are planets smaller than Neptune that are thought to be among the most common exoplanets in our solar system despite being unlike any other planet in our system. Because of the gravitational forces at play, planets are thought to form in resonance most of the time. However, perturbations like a passing star or a large asteroid or comet impact can easily upset this delicate equilibrium.
Systems such as HD110067 are of great interest to researchers because they can provide an image of what a system might look like in the absence of these dramatic events.
According to research by Rafael Luque of the University of Chicago, “we think only about 1% of all systems stay in resonance.” “It shows us the pristine configuration of a planetary system that has survived untouched.”