Kepler Observations of Three Pre-Launch Exoplanet Candidates: Discovery of Two Eclipsing Binaries and a New Exoplanet

TL;DR

This paper reports Kepler observations of three faint star candidates, identifying two as binary systems and confirming one as a new exoplanet, demonstrating a method to validate exoplanets without high-resolution radial velocity data.

Contribution

It introduces a novel approach to exclude false positives in faint star exoplanet candidates using Kepler data and reconnaissance spectroscopy, aiding large-scale follow-up.

Findings

Two candidates are binary star systems.

One candidate is a confirmed exoplanet with 1.12 R_Jupiter.

Method enables validation of faint star exoplanets without high-res radial velocities.

Abstract

Three transiting exoplanet candidate stars were discovered in a ground-based photometric survey prior to the launch of NASA's {\it Kepler} mission. {\it Kepler} observations of them were obtained during Quarter 1 of the {\it Kepler} mission. All three stars are faint by radial velocity follow-up standards, so we have examined these candidates with regard to eliminating false positives and providing high confidence exoplanet selection. We present a first attempt to exclude false positives for this set of faint stars without high resolution radial velocity analysis. This method of exoplanet confirmation will form a large part of the {\it Kepler} mission follow-up for Jupiter-sized exoplanet candidates orbiting faint stars. Using the {\it Kepler} light curves and pixel data, as well as medium resolution reconnaissance spectroscopy and speckle imaging, we find that two of our candidates are binary stars. One consists of a late-F star with an early M companion while the other is a K0 star plus a late M-dwarf/brown dwarf in a 19-day elliptical orbit. The third candidate (BOKS-1) is a $r$=15 G8V star hosting a newly discovered exoplanet with a radius of 1.12 R$_{Jupiter}$ in a 3.9 day orbit.