Search for exocomet transits in Kepler light curves

Ten new transits identified

¹ Institut d’astrophysique de Paris, CNRS, Sorbonne Université, 98 bis boulevard Arago, 75014 Paris, France
² CRAL, Ecole normale supérieure de Lyon, Université de Lyon, UMR, CNRS 5574, 69364 Lyon Cedex 07, France
³ LIRA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, 5 place Jules Janssen, 92195 Meudon, France
⁴ Institut Pierre-Simon Laplace, Sorbonne-Université, CNRS, Paris, France

^★ Corresponding author: pierre.dumond@ens-lyon.fr

Received: 19 June 2025
Accepted: 15 October 2025

Abstract

Although the Kepler telescope was retired over a decade ago, it continues to offer a rich dataset for uncovering new astrophysical objects and phenomena. In this study, we conducted a comprehensive search for exocometary transit signatures within the Kepler light curves, using a machine learning approach based on a neural network trained on a library of theoretical exocomet transit light curves. By analyzing the light curves of 201 820 stars, we identified candidate events through the neural network and subjected the output to filtering and visual inspection to mitigate false positives. Our results are presented in three catalogs of increasing ambiguity. The first tier catalog includes 17 high-confidence exocometary transit events, comprising seven previously reported events and ten newly identified ones, each associated with a different host star. The second tier catalog lists 30 lower-confidence events that remain consistent with possible exocometary transits. The third tier catalog consists of 49 more symmetric photometric events that could be exocometary transits, exoplanet mono-transits, or false positives due to eclipsing binaries mimicking transits. Contrary to previous studies, which suggested that the cometary activity was favored by stellar youth, we find a broad age distribution among candidate host stars, including several red giants. This challenges the general idea of a decline in cometary activity with stellar age and underlines the need for further investigation into the temporal evolution of exocometary activity in planetary systems.