This Rare Exoplanet System Has 6 ‘sub-Neptunes’ with Mathematically Perfect Orbits

Astronomers have discovered an unusual star system located just 100 light-years away from us, with six planets immensely close to their parent star - so close, in fact, that all their orbits could fit within the distance between the stars. Mercury and our sun. It's puzzling that this new part of the cosmos, unlike our own solar system, has remained largely unchanged since its birth over a billion years ago.

'If the galaxy was the Empire State Building, we would only be able to see and detect the planets next to it stars who have apartments on our floor," co-author Enric Palle of the Instituto de Astrofísica de Canarias told reporters at a press conference. "We just discovered our neighbor."

100 light years It may sound like quite a distance, but cosmically the system is incredibly close to us. Designated HD 110067, it is located in the constellation Coma Berenices, near Virgo in the northern sky.

And because the six planets in HD 10067 are so cozy with their rather bright, orange star, none lie in the habitable zone, the region around a star with the right conditions to support life as we know it. The planets also rotate very quickly, so their "years" range from 9 days to 55 days.

Related: Europe's planet-hunting CHEOPS telescope spies its first alien worlds

Scale animation of the orbits of the six newly discovered planets in the HD110067 system, about 100 light-years from Earth. The pitch of the notes played as each planet transits corresponds to the resonant change in orbital frequencies between each successive planet. (Video credit: animation, composition and annotations by Dr. Hugh Osborn (University of Bern), background image by NASA/MIT/TESS and Ethan Kruse)

First discovered in 2020 by NASA's Transiting Exoplanet Survey Satellite ( TESS), astronomers realized early on that they were dealing with at least two so-called sub-Neptunesthese are planets that are about two to three times the size of Soil and apparently covered by swollen spheres. The northern sky would disappear below the horizon shortly after TESS's detection, meaning the team had only about a month to confirm the discovery using ground-based telescopes, said co-author Rafael Luque of the University of Chicago.

Then, with new data from TESS collected when it revisited the same patch of sky two years later, plus an 'orchestrated campaign' focused on the star for more detailed observations by the European Space Agency's Characterizing exoplanet satellite ( Cheops), scientists confirmed a third exoplanet in the system.

The remaining three outer planets are attributed in TESS data to unprecedented dips in starlight, known to be caused by orbiting planets, thanks to the orbits of all three confirmed planets existing almost perfectly in what scientists call resonance. That is, the first planet makes three orbits for every two of the second planet. The exact same dynamic plays out between the next two planets. It is calculated that the fourth planet makes four orbits for every three of the fifth planet, which in turn makes four orbits around the star for every three of the outer planets.

In our own solar system, Pluto is in a similar resonance with Neptune (it orbits our Sun twice for every three orbits of Neptune).

"This system will help us answer questions without having to sort through all the different exoplanet systems," Keighley Rockcliffe, a graduate student who studies the atmospheres of exoplanets at Dartmouth College in New Hampshire and who was not involved in the new research, told Space. com. Because the six planets orbit the same star and their locations do not appear to have changed since formation, astronomers can use just this one system to better understand the formation and evolution processes of planetary systems by comparing various parameters of the six planets, including their compositions . Rockcliffe said.

"It's as if studying a plant - perhaps the petal colors of a flower - can tell us about the soil from which it grew," she said. "So HD 110067 has a lot of exciting things to offer!"

Luque, the first to be informed of the confirmation of the outer planets by colleagues at NASA Ames Research Center recalled sharing the news with the rest of the team via a conference call.

"I could hear the sigh in the room even through my headphones when there were no microphones around," he said. "You could tell it was a really nice discovery."

This perfectly resonant system with its long chain of planets is a rare find. It's something "we learn at school, but we don't really think it applies to nature," says co-author Hugh Osborn of the University of Bern, who remembers being "shocked and delighted" when he first heard of the discovery. "Often we make predictions, and nature finds a way to do something different that doesn't quite match what we expect."

Planets begin in resonance when they are born from dusty protoplanetary disks, but those delicate orbits often become unbalanced as stars pass from outside or dominate planets, larger than others within the system, get too close. This has also happened in our solar system, but it appears that HD 110067 remained impressively robust during such interruptions.

"We had used mathematical theory to predict these orbits and nature really matched these beautiful, perfect breaks," Osborn said. "That was a beautiful moment."

Studying the planets could even shed light on why many solar systems, including ours, do not have a sub-Neptune, despite this type of planet being the most common type in the world. Milky Way. In our corner of the cosmos, Jupiter It is believed to have played a decisive role in shaping the early evolution of our system and its planets, possibly gobbling up all available material so that a sub-Neptune-sized planet had no chance to merge .