Where can we find Super-Earths?

TL;DR

This paper investigates the likely locations of Super-Earths in planetary systems with gas giants, highlighting how their positions relative to the gas giants influence their orbital resonances and trapping mechanisms, which aids observational detection.

Contribution

It provides new insights into the orbital dynamics of Super-Earths near gas giants, especially regarding resonance locking and trapping at the gap edges in protoplanetary discs.

Findings

Super-Earths can become locked in mean motion resonance when inside the gas giant.

External Super-Earths are trapped at the outer edge of the gap, avoiding first-order resonances.

The results are relevant for improving Transit Timing Variation detection methods.

Abstract

In recent years we have been witnessing the discovery of one extrasolar gas giant after another. Now the time has come to detect more low-mass planets like Super-Earths and Earth-like objects. An interesting question to ask is: where should we look for them? We have explored here the possibility of finding Super-Earths in the close vicinity of gas giants, as a result of the early evolution of planetary systems. For this purpose, we have considered a young planetary system containing a Super-Earth and a gas giant, both embedded in a protoplanetary disc. We have shown that, if the Super-Earth is on the internal orbit relative to the gas giant, the planets can easily become locked in a mean motion resonance. This is no longer true, however, if the Super-Earth is on the external orbit. In this case we have obtained that the low-mass planet is captured in a trap at the outer edge of the gap opened by the giant planet and no first order mean motion commensurabilities are expected. Our investigations might be particularly useful for the observational TTV (Transit Timing Variation) technique.