Top panel: H α line profile at spectral resolution R = 1.5 × 10⁶ for one case in the Polar-Cold scenario with Ṁ = 3 × 10⁻⁵ M_J yr⁻¹, M_p = 10 M_J, and R_p = 2.04 R_J (solid red line) when observing into the accreting area at 150 pc. The flux in the absence of absorption by the incoming matter is also shown (dashed green line). The background colour shows as a function of distance from the planet (right vertical axis) and observer-frame wavelength the strength of the absorption by the gas (Eq. (16)), capped at . Few regions have a higher , the main onebeing the H I resonance near the shock (reaching ). Indicated are also the central peak of the H α line in the rest frame λ_{H α} (vertical dotted grey line) and, as a function of radial distance from the planet, the wavelength that becomes blueshifted to λ_{H α} (see Eq. (15); curved solid grey line). No dust nor ISM extinction is included. Over the brighter region at r = 15–30 R_J, the temperature is T ≈ 2000–1500 K and the pressure P ≈ 1–0.2 erg cm⁻³ (cf. Fig. 3). Bottom panel: extinction A_λ from the accretion flow against velocity offset relative to H α.