Background Short-period Eclipsing Binaries in the Original Kepler Field

Abstract

Abstract During the primary Kepler mission, between 2009 and 2013, about 150,000 preselected targets were observed with a 29.42 minute long cadence. However, a survey of background stars that fall within the field of view (FOV) of the downloaded apertures of the primary targets has revealed a number of interesting objects. In this paper, we present the results of this search, focusing on short-period eclipsing binary (SPEB) stars in the background pixels of primary Kepler targets. We used Lomb–Scargle and Phase Dispersion Minimization methods to reveal pixels that show significant periodicities, resulting in the identification of 547 previously unknown faint SPEBs, mostly W UMa–type stars, and almost doubling the number of SPEBs in the original Kepler FOV. We prepared the light curves for scientific analysis and cross-matched the pixel coordinates with Gaia and other catalogs to identify the possible sources. We have found that the mean of the brightness distribution of the new background SPEBs is ∼4–5 mag fainter than other, primary target eclipsing binaries in the Kepler Eclipsing Binary catalog. The period distribution nonetheless follows the same trend, but the spatial distribution appears to be different from that described by Kirk et al. for the catalog eclipsing binaries.