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TOPIC: TrES-3


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Posts: 131433
Date:
TrES-3b
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Title: Photometric Investigation of Hot Exoplanets: TrES-3b and Qatar-1b
Author: Caglar Püsküllü, Faruk Soydugan, Ahmet Erdem, Edwin Budding

New photometric follow-up observations of exoplanet transits of 'hot Jupiters' TrES-3b and Qatar-1b are presented. Weighted mean values of the solutions of light curves in R-fiter for both planetary systems are reported and compared with the previous results. The transit light curves were analysed using the WINFITTER code. The physical properties of the planets were estimated. The planet radii are found to be R_p=1.381±0.033R_J for TrES-3b and R_p=1.142±0.025R_J for Qatar-1b. Transit times and their uncertainties were also determined and a new linear ephemeris was computed for both systems. Analysis of transit times showed that a significant signal could not be determined for TrES-3b, while weak evidence was found for Qatar-1b, which might be tested using more precise future transit times.

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Posts: 131433
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RE: TrES-3
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Title: Follow-up photometry of TrES-3
Authors: M. Vanko, G. Maciejewski, M.Jakubik, T. Krejcova, J. Budaj, T. Pribulla, J. Ohlert, St. Raetz, S. Parimucha, L. Bukowiecki

We present new observations of the transiting system TrES-3 obtained from 2009 to 2011 at several observatories. The orbital parameters of the system were re- determined and a new linear ephemeris was calculated. The best quality light curve was used for light curve analysis, an other datasets were used to determine mid-transit times, Tc, and study transit time variation (TTV). For planet parameter determination we used two independent codes and finally, we concluded that our parameters are in agreement with previous studies. Based on our observations, we determined 14 mid-transit times. Together with published Tc we found that the timing residuals showed no significant deviation from the linear ephemeris. We concluded that a periodic TTV signal with an amplitude greater than 1 minute over a 4-year time span seems to be unlikely. Our analysis of an upper mass limit allows us to exclude an additional Earth-mass planet close to inner 3:1, 2:1, and 5:3 and outer 3:5, 1:2, and 1:3 mean-motion resonances. Using the long-term integration and applying the method of maximum eccentricity, the region from 0.015 au to 0.05 au was found unstable and the region beyond the 0.05 au was found to have a chaotic behaviour and its depletion increases with increasing values of the initial eccentricity as well as inclination.

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Posts: 131433
Date:
TrES-3b
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Title: APOSTLE: Eleven Transit Observations of TrES-3b
Authors: Praveen Kundurthy, Andrew C. Becker, Eric Agol, Rory Barnes, Benjamin F. Williams

The Apache Point Survey of Transit Lightcurves of Exoplanets (APOSTLE) observed eleven transits of TrES-3b over two years in order to constrain system parameters and look for transit timing and depth variations. We describe an updated analysis protocol for APOSTLE data, including the reduction pipeline, transit model and Markov Chain Monte Carlo analyser. Our estimates of the system parameters for TrESb are consistent with previous estimates to within the 2\sigma\ confidence level. We improved the errors (by 10--30%) on system parameters like the orbital inclination (i_{orb}), impact parameter (b) and stellar density (rho_{\star}) compared to previous measurements. The near-grazing nature of the system, and incomplete sampling of some transits, limited our ability to place reliable uncertainties on individual transit depths and hence we do not report strong evidence for variability. Our analysis of the transit timing data show no evidence for transit timing variations and our timing measurements are able to rule out Super-Earth and Gas Giant companions in low order mean motion resonance with TrES-3b.

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Posts: 131433
Date:
TrES-3
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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)

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 chi²  = 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.

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