Background exoplanet candidates in the original Kepler field

Abstract

Context. During the primary Kepler mission, between 2009 and 2013, about 150 000 pre-selected targets were observed with a 29.42 minute-long cadence. However, a survey of background stars that fall within the field of view of the downloaded apertures of the primary targets has revealed a number of interesting objects. In previous papers we have presented surveys of short-period eclipsing binaries and RR Lyrae stars.Aims. The current survey of the Kepler background is concentrated on identifying longer-period eclipsing binaries and pulsating stars. These will be the subject of later papers. In the course of this survey, in addition to eclipsing binaries and pulsating stars, seven exoplanet candidates have been uncovered and in this paper we report on these candidates.Methods. We used Lomb-Scargle, light curve transit search, and phase dispersion minimisation methods to reveal pixels that show significant periodicities, resulting in the identification of the seven exoplanet candidates. We prepared the light curves for analysis using Pytransit software and cross-matched the pixel coordinates with Gaia and other catalogues to identify the sources.Results. We identify seven hot Jupiter exoplanet candidates with planet radii ranging from 0.8878 to 1.5174 R_{Jup and periods ranging from 2.5089 to 4.7918 days.}