A Planetary System With Six Sub-Neptunes Locked in Perfect Resonance

Scientists used data from NASA’s TESS and ESA’s Cheops to find and confirm the system, which orbits K0-type star HD110067.

Beth Johnson

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Credit: Thibaut Roger/NCCR PlanetS

A team of researchers led by University of Chicago astronomer Rafael Luque analyzed data acquired by both NASA’s Transiting Exoplanet Survey Satellite (TESS) and ESA’s CHaracterising ExOPlanet Satellite (Cheops) and found a unique planetary system. Orbiting a star cataloged as HD110067, this system contains six sub-Neptune planets. Incredibly, all six planets are orbiting in direct resonance with each other. The results of the work were published on November 29 in Nature.

In 2020, transit data collected by TESS, which tracks the change in the star’s brightness, revealed at least two planets. Their orbits were about nine days for the closer and fourteen days for the farther world. Additionally, the transits provided hints of several more planets. Then follow-up data from Cheops identified a third planet orbiting in twenty days.

From these orbital periods, Luque realized that these three planets orbited in a 3/2 resonance with each other. Planet b, the innermost, orbits three times in the same amount of time that planet c, the next one out, orbits twice. Planet c orbits three…

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Beth Johnson

Planetary scientist, podcast host. Communication specialist for SETI Institute and Planetary Science Institute. Buy me a coffee: https://ko-fi.com/planetarypan