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

TL;DR

This paper discusses the challenges of identifying true transiting exoplanets amidst false positives in wide-field surveys, detailing procedures to reject impostors and highlighting the discovery of two planets including TrES-2.

Contribution

The paper introduces a systematic method for rejecting astrophysical false positives in transit surveys and reports the discovery of two transiting exoplanets, including TrES-2.

Findings

Development of a false positive rejection procedure

Identification of a blended binary system as a false positive

Discovery of two transiting exoplanets, including TrES-2

Abstract

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.