3:00 PM - 3:15 PM
[PPS06-18] The orbital stability of planets in resonances: the evolution of mass ratio
Keywords:orbital stability, mean motion resonance
The mass ratios between planets in close-in orbits and their central stars would not keep the same value after their formation. There are some mechanisms that super-Earths lose their envelopes, e.g., energy limited escape (Owen 2018). Also, young stars lose their mass by the stellar wind and coronal mass ejection (Cranmer 2017).
We perform simulations that the planets trapped in the first order resonant chain considering their mass ratio change. At first, planets migrate in the disk gas and are trapped in the resonant chain composed of the same resonant commensurability. Then, the disk gas is removed and the mass ratio between planets and the central star is changed, exponentially. When the number of planets in resonant chain exceeds the critical number corresponding resonant chain, their crossing time increases as the mass ratio decreases since the separation normalized by Hill radii becomes larger. In the cases that the resonant systems hold less planets than the critical number, planets sometimes cause orbital instability when their mass ratios change. In some conditions, the orbits of planets in resonant chain become unstable, when their mass ratios decrease only a few percent. Such instabilities tend to occur in systems that hold more planets.