Transit polarization in exoplanetary systems

Recently, polarimetry has become a promising method in the field of exoplanets, in particular with their detection and characterization. At KIS in the Hotmol group, we investigated how transiting exoplanets might induce some polarimetric effects by breaking the symmetry of the intensity integrated over the stellar disk. More specifically, this study produced models and focused on linear polarization. As these stars are also likely to have stellar spots able to break this symmetry, we took their presence into account in our models.

The figure presents the maximum polarization degree during transits for 88 exoplanetary systems as a function of host star surface gravity. The color scale refers to the effective temperature. The size of each circle designates the planet-to-star radii ratio (in the range from 0.1 to 0.17). The top, middle and bottom plots show the maximum polarization degree at wavelengths of 4000Å, 4500Å and 5000Å, respectively. The left plots were simulated assuming 200 data points per transit and the right plots 10 points per transit. The horizontal dashed line marks the lower limit (3σ) of achievable polarization sensitivity.

Kostogryz N.M., Yakobchuk T.M., Berdyugina S.V., 2015, ApJ
(accepted for publication)