Five Kepler target stars that show multiple transiting exoplanet candidates

TL;DR

This paper reports five Kepler candidate exoplanetary systems with multiple transiting objects, discusses detection methods, false-positive rejection, and implications for planetary system formation and dynamics.

Contribution

It introduces five new multi-planet candidate systems from Kepler data and analyzes their orbital configurations and potential for transit timing variations.

Findings

One system has three transiting candidates.

Three systems have candidates near mean motion resonances.

Most systems are expected to show detectable TTVs with more data.

Abstract

We present and discuss five candidate exoplanetary systems identified with the Kepler spacecraft. These five systems show transits from multiple exoplanet candidates. Should these objects prove to be planetary in nature, then these five systems open new opportunities for the field of exoplanets and provide new insights into the formation and dynamical evolution of planetary systems. We discuss the methods used to identify multiple transiting objects from the Kepler photometry as well as the false-positive rejection methods that have been applied to these data. One system shows transits from three distinct objects while the remaining four systems show transits from two objects. Three systems have planet candidates that are near mean motion commensurabilities---two near 2:1 and one just outside 5:2. We discuss the implications that multitransiting systems have on the distribution of orbital inclinations in planetary systems, and hence their dynamical histories; as well as their likely masses and chemical compositions. A Monte Carlo study indicates that, with additional data, most of these systems should exhibit detectable transit timing variations (TTV) due to gravitational interactions---though none are apparent in these data. We also discuss new challenges that arise in TTV analyses due to the presence of more than two planets in a system.