Many gaseous exoplanets in short-period orbits are on the verge or are in the process of Roche-lobe overflow (RLO). Moreover, orbital stability analysis shows tides can drive many hot Jupiters to spiral inevitably toward their host stars.
In this study, we showed that the evolution is largely determined by the core mass of the overflowing gas giant and that the orbital expansion that accompanies RLO often stops and reverses at a specific maximum period that depends on the core mass.
We suggest that RLO may often strand the remnant of a gas giant near this orbital period, and we conduct a preliminary comparison of this prediction to the observed population of small, short-period planets and find some planets in orbits that may be consistent with this picture (shown in the above figure).
To the extent that we can establish some short-period planets are indeed the remnants of gas giants, that population can elucidate the properties of gas giant cores, the properties of which remain largely unconstrained.
- Jackson et al. (2016) “Tidal Decay and Stable Roche-Lobe Overflow of Short-Period Gaseous Exoplanets.” CeMDA.
- Github repository
- Model Codes and Results