More Likely Than You Think: Inclination-Driving Secular Resonances are Common in Known Exoplanet Systems

Understand

Multi-planet systems face significant challenges to detection.

• For example, further orbiting planets have reduced signal-to-noise ratio in radial velocity detection methods, and small mutual inclinations between planets can prevent them from all transiting.
• One mechanism to excite mutual inclination between planets is secular resonance, where the nodal precession frequencies of the planets align such as to greatly increase the efficiency of angular momentum transport between planets.
• These resonances can significantly misalign planets from one another, hindering detection, and typically can only occur when there are three or more planets in the system.