Binary stars can throw planetary orbits into chaos

Planets go through a process known as precession, where the angle of their orbital tracks around a star changes over time. This is a very slow process, requiring many orbits to complete.

The part that isn’t generally covered in introductory astronomy courses is what happens to precession in binary star systems. For distant companions, the orbit is very long, and thus the change in gravitational influences is slow. In some cases, the two processes can be close to a match with each other, taking roughly the same amount of time to cycle. This led a group of researchers to wonder if they could be so close as to get into a resonance. If so, it could have profound effects for the planets. To find out, the researchers constructed a numerical simulation.

According to the simulation, planetary orbits are indeed susceptible to perturbation from the companion star. As the researchers suspected, this can happen when a planet’s precession is resonant with the companion star’s orbital motion.