The bright nearby star HD 110067 hosts six transiting sub-Neptunes that follow a chain of resonant orbits, according to new research led by University of Chicago astronomers.
HD 110067 is a bright K0-type star located 100 light-years away in the constellation of Coma Berenices.
Otherwise known as TIC 347332255, the star has a mass and radius about 80% of the Sun’s.
In 2020, NASA’s Transiting Exoplanet Survey Satellite (TESS) detected dips in the star’s brightness that indicated planets were passing in front of the star’s surface.
A preliminary analysis revealed two possible planets: one with an orbital period of 5.642 days and the other with a period that could not be determined yet.
In 2022, TESS observed the same star again. Analyzing the combined data sets ruled out the original interpretation but presented two different possible planets.
While these detections were much more certain than the originals, there was a lot about the TESS data that still did not make sense.
“That’s when we decided to use ESA’s CHaracterising ExOPlanet Satellite (Cheops),” said lead author Dr. Rafael Luque, an astronomer in the Department of Astronomy and Astrophysics at the University of Chicago.
“We went fishing for signals among all the potential periods that those planets could have.”
They confirmed a third planet in the system and realized that they had found the key to unlocking the whole system because it was now clear that the three planets were in an orbital resonance.
The outer-most planet, HD 110067d, takes 20.519 days to orbit, which is extremely close to 1.5 times the orbital period of the next planet, HD 110067c, with 13.673 days.
This in turn is almost exactly 1.5 times the orbital period of the inner planet, HD 110067b, with 9.114 days.
Predicting other orbital resonances and matching them to the remaining unexplained data allowed Dr. Luque and his colleagues to discover the other three planets in the system: HD 110067e,…
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