Fig. 4: Effect of surface magnetic field on transit depth for the exemplary case of a Jupiter-size planet transiting a solar twin.
From: Magnetic origin of the discrepancy between stellar limb-darkening models and observations
a–f, The difference in the depth of the transit (ΔDepth) calculated with the darkening of the limb corresponding to different degrees of magnetization (different colours) with respect to the darkening of the non-magnetic limb (HD) in ppm. The two columns show the ΔDepth at wavelengths shorter than (a,c,e) and longer than (b,d,f) 1,000 nm. The three rows correspond to different impact parameters (b = 0.0 (a,b), b = 0.5 (c,d) and b = 0.9 (e,f)) describing the transit path, which is schematically shown in the top-right corner of a, c and e. The bigger circle represents the star and the smaller represents the planet. In general, the difference in transit depth is always larger for stronger average stellar fields and is largest in the ultraviolet while decreasing towards longer wavelengths.
