Up until now, we have discovered hundreds of stars with many planets orbiting them in the galaxy. Each and every one of them is unique, but there is one that has caught the attention of astronomers: one orbiting the star HD 158259, that’s 88 light-years away.
The star has the same mass, but it’s a bit larger than the Sun, and there are six planets that orbit it: a super-Earth and five mini-Neptunes.
After keeping an eye on it for seven years, astronomers discovered that all of the six planets that orbit HD 158259 are doing so in perfect orbital resonance. This discovery helped us to better understand how the planetary system formed, and how they ended up the configurations we see.
Orbital resonance happens when the orbits of two bodies are closely linked, as the two orbiting bodies exert gravitational influence on each other. It’s quite rare in our Solar System for this to happen. The best example is represented by Pluto and Neptune. Every lap that Pluto makes around the Sun means three for Neptune.
The SOPHIE spectrograph and the TESS space telescope helped in calculating the orbits of each planet. The super-Earth has twice the mass of Earth. “Several compact systems with several planets in, or close to, resonances are known, such as TRAPPIST-1 or Kepler-80. Such systems are believed to form far from the star before migrating towards it. In this scenario, the resonances play a crucial part.”
Scientists think that the resonances come when planetary embryos grow and migrate inwards away from the outer edge of the disc. This is what produces a chain of orbital resonance throughout the system. The orbital resonances could how us more about when destabilization happens.