How a binary star system disrupts a planet’s orbit
doi:10.1038/nindia.2015.127 Published online 14 September 2015
Researchers have discovered a new astrophysical phenomenon by which one star in a binary star system can disrupt the orbits of planets1. This phenomenon can be so strong that it can cause a planet to escape the gravity of its star.
Binary star systems in which two stars orbit each other are common. Although planets trapped by the gravity of such stars only revolve around one of the stars, they are affected by the gravity of the other star.
To better understand how binary systems disrupt planetary motion, the researchers performed numerical simulations based on a mathematical model they had developed. They computed the orbital periods of 124 multiple-planet systems with minimum planetary masses. Their simulations predicted that for larger masses, the distribution of planets will shift towards shorter periods.
The researchers found that the periods of planetary orbital precessions were close to the orbital period of the binary companion star, giving rise to a phenomenon known as ‘orbital resonance’.
Armed with this knowledge, the researchers simulated the scenario of a companion star orbiting the Sun and found that Saturn would be captured by orbital resonance, greatly disturbing the outer solar system.
The researchers say that such resonance can reduce the multiplanet occurrence rate in wide binaries and may affect planet formation in close binaries.
1. Touma, J. R. et al. The disruption of multiplanet systems through resonance with a binary orbit. Nature 524, 439–441 (2015)