On the Apparent Orbital Inclination Change of the Extrasolar Transiting Planet TrES-2b

Abstract

On June 15, 2009 UT the transit of TrES-2b was detected using the University of Arizona's 1.55 meter Kuiper Telescope with 2.0-2.5 millimag RMS accuracy in the I-band. We find a central transit time of $T_c=2454997.76286\pm 0.00035$ HJD, an orbital period of $P=2.4706127\pm 0.0000009$ days, and an inclination angle of $i=83^{\circ }.92\pm 0.05$, which is consistent with our re-fit of the original I-band light curve of O'Donovan et al. (2006) where we find $i=83^{\circ }.84\pm 0.05$. We calculate an insignificant inclination change of $\Delta i=-0^{\circ }.08\pm 0.07$ over the last 3 years, and as such, our observations rule out, at the $\sim 11\sigma$ level, the apparent change of orbital inclination to $i_{predicted}=83^{\circ }.35\pm 0.1$ as predicted by Mislis and Schmitt (2009) and Mislis et al. (2010) for our epoch. Moreover, our analysis of a recently published Kepler Space Telescope light curve (Gilliland et al. 2010) for TrES-2b finds an inclination of $i=83^{\circ }.91\pm 0.03$ for a similar epoch. These Kepler results definitively rule out change in $i$ as a function of time. Indeed, we detect no significant changes in any of the orbital parameters of TrES-2b.

19 pages, 1 table, 7 figures. Re-submitted to ApJ, January 14, 2010