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Astrophysics > Earth and Planetary Astrophysics

Title: A transit timing analysis of nine RISE light curves of the exoplanet system TrES-3

Authors: N. P. Gibson (1), D. Pollacco (1), I. Skillen (2), E. K. Simpson (1), S. Barros (1), Y. C. Joshi (1), I. Todd (1), C. Benn (2), D. Christian (1), M. Hrudková (3), F. P. Keenan (1), I. A. Steele (4) ((1) Queen's University Belfast, (2) Isaac Newton Group of Telescopes, (3) Charles University Prague, (4) Liverpool John Moores University)
Abstract: We present nine newly observed transits of TrES-3, taken as part of a transit timing program using the RISE instrument on the Liverpool Telescope. A Markov-Chain Monte-Carlo analysis was used to determine the planet-star radius ratio and inclination of the system, which were found to be Rp/Rstar=0.1664^{+0.0011}_{-0.0018} and i = 81.73^{+0.13}_{-0.04} respectively, consistent with previous results. The central transit times and uncertainties were also calculated, using a residual-permutation algorithm as an independent check on the errors. A re-analysis of eight previously published TrES-3 light curves was conducted to determine the transit times and uncertainties using consistent techniques. Whilst the transit times were not found to be in agreement with a linear ephemeris, giving chi^2 = 35.07 for 15 degrees of freedom, we interpret this to be the result of systematics in the light curves rather than a real transit timing variation. This is because the light curves that show the largest deviation from a constant period either have relatively little out-of-transit coverage, or have clear systematics. A new ephemeris was calculated using the transit times, and was found to be T_c(0) = 2454632.62610 +- 0.00006 HJD and P = 1.3061864 +- 0.0000005 days. The transit times were then used to place upper mass limits as a function of the period ratio of a potential perturbing planet, showing that our data are sufficiently sensitive to have probed for sub-Earth mass planets in both interior and exterior 2:1 resonances, assuming the additional planet is in an initially circular orbit.
Comments: 21 pages, 4 figures, Accepted for publication in ApJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Journal reference: Astrophys.J.700:1078-1085,2009
DOI: 10.1088/0004-637X/700/2/1078
Cite as: arXiv:0905.4680 [astro-ph.EP]
  (or arXiv:0905.4680v1 [astro-ph.EP] for this version)

Submission history

From: Neale Gibson [view email]
[v1] Thu, 28 May 2009 16:07:25 GMT (58kb)