The population of long-period transiting exoplanets

TL;DR

This study develops an automated method to detect long-period exoplanets with one or two transits in Kepler data, revealing 16 candidates and estimating their occurrence rate around Sun-like stars.

Contribution

The paper introduces a fully automated search technique for long-period transiting exoplanets, expanding detection capabilities beyond short-period planets in Kepler data.

Findings

Identified 16 long-period exoplanet candidates, including 6 new discoveries.

Estimated the occurrence rate of such exoplanets as 2.0±0.7 per Sun-like star.

Demonstrated no human intervention is needed for detection, enabling scalable searches.

Abstract

The Kepler Mission has discovered thousands of exoplanets and revolutionized our understanding of their population. This large, homogeneous catalog of discoveries has enabled rigorous studies of the occurrence rate of exoplanets and planetary systems as a function of their physical properties. However, transit surveys like Kepler are most sensitive to planets with orbital periods much shorter than the orbital periods of Jupiter and Saturn, the most massive planets in our Solar System. To address this deficiency, we perform a fully automated search for long-period exoplanets with only one or two transits in the archival Kepler light curves. When applied to the $\sim 40,000$ brightest Sun-like target stars, this search produces 16 long-period exoplanet candidates. Of these candidates, 6 are novel discoveries and 5 are in systems with inner short-period transiting planets. Since our method involves no human intervention, we empirically characterize the detection efficiency of our search. Based on these results, we measure the average occurrence rate of exoplanets smaller than Jupiter with orbital periods in the range 2-25 years to be $2.0\pm0.7$ planets per Sun-like star.