Absorption profiles during the transit (top panel) and the post-transit (bottom panel) of HD 189733b. The absorption signature observed in 2011 at high velocities in the blue wing of the Lyman-α line is delimited by vertical black dotted lines (blue histogram; Lecavelier des Etangs et al. 2012 and Bourrier et al. 2013). Two absorption profiles are calculated for best-fit parameters (ionizing flux F_ion = 10  F_⊙) in the saturation regime (solid line: escape rate Ṁ = 10⁹ g s^-1 and proton density n_wind = 10⁶ cm^-3) and out of this regime (dashed line: escape rate Ṁ = 8 × 10¹⁰ g s^-1 and proton density n_wind = 2 × 10³ cm^-3). The main difference between the two profiles is the absorption at the center of the line, which is significantly reduced in the saturation regime, although for HD 189733b the Lyman-α flux at these wavelengths is in any case completely absorbed by the blueshifted ISM (see Fig. 1). The simulated planetary disk causes an absorption depth of ~2.3% at all wavelengths during the transit.