Simulation of polarimetric effects in planetary system HD 189733

Abstract

In this paper we present results of linear polarization modelling for HD 189733 in the U filter using the Monte Carlo method. Our simulations are based on the well known effect that linear polarization of a entrosymmetri unresolved star becomes non-zero during the planet transit or in the presene of spots on its surface. HD 189733 is urrently the brightest (mᵥ = 7.67ᵐ ) known star to harbour a transiting exoplanet. This fat, along with the short orbital period (2.2 d), makes it very suitable for different types of observations in luding polarimetry. Sine we are interested in oultation effects, a very important parameter is the ratio of the planet to star radii, which is also very large (0.15). As the host star is active and spots may over up to 1% of the planetary surfae, we perform our simulations for different spot parameters such as sizes, locations on the stellar disk, and temperatures.