Numerous exoplanets are orbiting their host star in a very unusual but precise “rhythm”. Scientists made this discovery by focusing on the system’s rhythmic orbital dance.
When astronomers analyzed data collected by NASA’s Transiting Exoplanet Survey Satellite (TESS), they initially discovered three planets orbiting a star called TOI-178. But when they looked more closely at the system, they found that the planets were orbiting in a type of precise rhythm with each other. And after further analysis, they discovered that there are at least six planets in the system.
What’s even more interesting is that the planets are very different from one another. Experts were able to determine that these six planets are anywhere from 1.1 times to 3 times larger than Earth and they all have different densities, from being a rocky super-Earth-like planet to a gassy mini-Neptune.
In a statement provided by the University of Bern in Switzerland, Kate Isaak, who is the project scientist for the European Space Agency’s Characterizing Exoplanet Satellite (CHEOPS), explained this discovery in further detail, “It is the first time we observe something like this,” adding, “In the few systems we know with such a harmony, the density of planets steadily decreases as we move away from the star. In the TOI-178 system, a dense, terrestrial planet like Earth appears to be right next to a very fluffy planet with half the density of Neptune, followed by one very similar to Neptune.”
As for the planets that travel around TOI-178, they orbit the star every 2, 3, 6, 10, 15, and 20 days. According to the researchers’ analysis, the planet that is the closest to the star orbits in its own rhythm but the other five are in complete harmony with one another. To put the outer five planets’ rhythm into better perspective, when the planet the furthest from the star completes one orbit, the next closest planet completes three-quarters of its orbit, followed by the next closest making two orbits, then the next one completing three orbits, and the fifth one finishing six orbits. Furthermore, the planets sometimes line up while orbiting the star. (An artist’s impression of the TOI-178 system can be seen here as well as a video showing the planets’ unusually precise rhythm.)
And there may be even more planets orbiting TOI-178 but scientists will need to study the system in greater detail with help from the European Extremely Large Telescope and the James Webb Space Telescope.
Their research was published in the journal Astronomy & Astrophysics where it can be read in full.