System parameters, transit times and secondary eclipse constraints of the exoplanet systems HAT-P-4, TrES-2, TrES-3 and WASP-3 from the NASA EPOXI Mission of Opportunity

TL;DR

This study uses high-precision photometry from NASA's EPOXI mission to refine parameters and transit timings of four hot-Jupiter exoplanets, setting upper limits on secondary eclipse depths and analyzing atmospheric properties.

Contribution

First detailed transit analysis of four hot-Jupiter systems from EPOXI data, providing refined system parameters and secondary eclipse constraints.

Findings

Refined planetary and stellar radii and inclinations for all four systems.

Set upper limits on secondary eclipse depths, constraining atmospheric models.

Confirmed absence of temperature inversion in TrES-3's atmosphere.

Abstract

As part of the NASA EPOXI Mission of Opportunity, we observed seven known transiting extrasolar planet systems in order to construct time series photometry of extremely high phase coverage and precision. Here we present the results for four "hot-Jupiter systems" with near-solar stars - HAT-P-4, TrES-3, TrES-2 and WASP-3. We observe ten transits of HAT-P-4, estimating the planet radius Rp = 1.332 \pm 0.052 RJup, the stellar radius R \star = 1.602 \pm 0.061 R \odot, the inclination i = 89.67 \pm 0.30 degrees and the transit duration from first to fourth contact T = 255.6 \pm 1.9 minutes. For TrES-3, we observe seven transits, and find Rp = 1.320 \pm 0.057 RJup, R\star = 0.817 \pm 0.022 R\odot, i = 81.99 \pm 0.30 degrees and T = 81.9 \pm 1.1 minutes. We also note a long term variability in the TrES-3 light curve, which may be due to star spots. We observe nine transits of TrES-2, and find Rp = 1.169 \pm 0.034 RJup, R\star = 0.940 \pm 0.026 R\odot, i = 84.15 \pm 0.16 degrees and T = 107.3 \pm 1.1 minutes. Finally we observe eight transits of WASP-3, finding Rp = 1.385 \pm 0.060 RJup, R\star = 1.354 \pm 0.056 R\odot, i = 84.22 \pm 0.81 degrees and T = 167.3 \pm 1.3 minutes. We present refined orbital periods and times of transit for each target. We state 95% confidence upper limits on the secondary eclipse depths in our broadband visible bandpass centered on 650 nm. These limits are 0.073% for HAT-P-4, 0.062% for TrES-3, 0.16% for TrES-2 and 0.11% for WASP-3. We combine the TrES-3 secondary eclipse information with the existing published data and confirm that the atmosphere likely does not have a temperature inversion.