TrES Exoplanets and False Positives: Finding the Needle in the Haystack

Our incomplete understanding of the formation of gas giants and of their mass–radius relationship has motivated ground–based, wide–field surveys for new transiting extrasolar giant planets. Yet, astrophysical false positives have dominated the yield from these campaigns. Astronomical systems where the light from a faint eclipsing binary and a bright star is blended, producing a transit–like light curve, are particularly difficult to eliminate. As part of the Trans–atlantic Exoplanet Survey, we have encountered numerous false positives and have developed a procedure to reject them. We present examples of these false positives, including the blended system GSC 03885–00829 which we showed to be a K dwarf binary system superimposed on a late F dwarf star. This transit candidate in particular demonstrates the careful analysis required to identify astrophysical false positives in a transit survey. From amongst these impostors, we have found two transiting planets. We discuss our follow-up observations of TrES–2, the first transiting planet in the Kepler field.