© NASANASA's Transiting Exoplanet Survey Satellite (TESS)
For planet-hunting astronomers, finding a star system with six planets is rare enough, but one system recently spotted 100 light-years away has six planets that orbit in lock-step with one another.
The six planets orbit a star designed HD110067, which from the perspective of an Earth observer sits in the constellation Coma Berenices. It was first spotted as a potential planet-possessing star in 2020, when NASA's Transiting Exoplanet Survey Satellite (TESS) detected a distinct dip in its brightness - a telltale sign that a planet had passed in front of the star.
Once scientists combined the TESS data with that from the European Space Agency's CHaracterizing ExOPlanet Satellite (Cheops) telescope, they discovered that HD110067 was quite the gem. Their work was
published on Wednesday in
Nature.
"This discovery is going to become a benchmark system to study how sub-Neptunes, the most common type of planets outside of the solar system, form, evolve, what are they made of, and if they possess the right conditions to support the existence of liquid water in their surfaces," University of Chicago scientist and study lead author Rafael Luque said in
a news release.
"Sub-Neptunes" are planets larger than Earth, the largest rocky world in our solar system, but smaller than Neptune, the smallest gas giant in our solar system. Scientists think such worlds likely have solid cores and gaseous atmospheres. The rocky parallel to sub-Neptunes are
"super-Earths," which have solid crusts and thinner atmospheres.
© Roger Thibaut (NCCR PlanetS)An artist's illustration of the six newly discovered planets circling their star in resonance
The six planets orbit in resonance with one another: the planet closest to the star makes three orbits for every two made by the next closest planet, a 3/2 resonance. That pattern holds true for each of the four closest planets. For the outer two, they follow a 4/3 resonance pattern - that is, the fifth planet makes three orbits for every four orbits the fourth planet makes, and the outermost planet makes three orbits for every four orbits the fifth planet makes.
According to the scientists, these planets have maintained this pattern for billions of years, and likely settled into it as they were still forming. That means that unlike our solar system, there probably weren't any "rogue planets" or major events to perturb their orbits after they formed.
"We think only about one percent of all systems stay in resonance, and even fewer show a chain of planets in such configuration," said Luque, who added that was why HD110067 merits further study. "It shows us the pristine configuration of a planetary system that has survived untouched."
Some moons in our solar system have also been found to have orbital resonances around their host planets, such as
Jupiter's moons Io, Europa and Ganymede. Neptune and the
dwarf planet Pluto also orbit the Sun in a 2/3 resonance.
Reader Comments
Truly the music of the spheres, Pythogoras was right
Resonance seems way too strong a word when people are talking:
" gee, this planet orbits once every 2.3 times the other planet orbits ! "
It's much like archaeology where they find a small trinket and immediately say it had some religious significance.
Because we all know the ancients sat around pondering the gods all day long.
A new toy, a new day, a new dawn and the same load of BOLLOCKS.
It is beyond doubt that electromagnetic force play an important part in the behavior of stellar bodies. No scientist denies the geomagnetic field, or the strong EM fields emanated from the sun. But yet they omit it in their theories.
Maybe the orbits have been stable because any interlopers get smashed to pieces