Interpretation of the Transit Light Curve in the Presence of Principal Main Minimum with Allowance for the Eccentricity of the Transit (Planet) Orbit

Abstract

Using a high-precision algorithm for interpreting transit light curves in a model of a classical eclipsing binary star-exoplanet system, we studied the possibility of determining the system parameters in the absence of a priori knowledge of the orbital eccentricity. It was shown that it is impossible to determine the exact value of the eccentricity and periastron longitude based on the main minimum of the transit light curve alone. Also, at an observational accuracy of ~1% of the eclipse depth, the uncertainty in the eccentricity and periastron longitude together causes a significant uncertainty in the values of the component radii (a two-threefold error relative to the true values) and the orbital inclination angle. However, the ratios of the system component radii and the limb darkening coefficients are determined with good accuracy. At an increase in the observational accuracy to 0.1% of the eclipse depth, it becomes possible to determine the component radii and the orbital inclination angle when interpreting the light curve with allowance for the eccentricity.