We present four new transits of the planetary system TrES-3 observed between 2009 May and 2010 June .
Among these , the third transit by itself indicates possible evidence for brightness disturbance , which might be the result of the planet blocking a cool starspot on the stellar surface .
A total of 109 transit times , including our measurements , were used to determine the improved ephemeris with a transit epoch of 2454185.910944 \pm 0.000072 HJED and an orbital period of 1.30618700 \pm 0.00000015 d. We analyzed the transit light curves using the JKTEBOP code and adopting the quadratic limb-darkening law .
In order to derive the physical properties of the TrES-3 system , the transit parameters are combined with the empirical relations from eclipsing binary stars and stellar evolutionary models .
The stellar mass and radius obtained from a calibration using T _ { A } , log \rho _ { A } and [ Fe/H ] are consistent with those from the isochrone analysis .
We found that the exoplanet TrES-3b has a mass of 1.93 \pm 0.07 M _ { Jup } , a radius of 1.30 \pm 0.04 R _ { Jup } , a surface gravity of log g _ { b } =3.45 \pm 0.02 , a density of 0.82 \pm 0.06 \rho _ { Jup } , and an equilibrium temperature of 1641 \pm 23 K. The results are in good agreement with theoretical models for gas giant planets .