A statistical search for a population of Exo-Trojans in the Kepler dataset

TL;DR

This study searches for exo-Trojans in the Kepler dataset by stacking thousands of planet transits, setting upper limits on Trojan sizes and identifying potential signals for larger Trojans around longer-period planets.

Contribution

It introduces a super-stacking method to statistically search for exo-Trojans and provides the first upper limits on their transiting sizes in Kepler data.

Findings

Upper limit on Trojan radius: <460 km at 2σ confidence

Significant Trojan-like signal detected for planets with periods >60 days

Results suggest potential for larger Trojans around longer-period planets

Abstract

Trojans are small bodies in planetary Lagrangian points. In our solar system, Jupiter has the largest number of such companions. Their existence is assumed for exoplanetary systems as well, but none has been found so far. We present an analysis by super-stacking $\sim4\times10^4$ Kepler planets with a total of $\sim9\times10^5$ transits, searching for an average trojan transit dip. Our result gives an upper limit to the average Trojan transiting area (per planet) corresponding to one body of radius $<460$km at $2\sigma$ confidence. We find a significant Trojan-like signal in a sub-sample for planets with more (or larger) Trojans for periods $>$60 days. Our tentative results can and should be checked with improved data from future missions like PLATO2.0, and can guide planetary formation theories.