Zoom-in on the planet, a 2D slice of the orbital midplane, with cells indicated by optical depths greater than 10⁻³, 10⁻², and 10⁻¹ (from dark to light, top). The observer is located in the –x and the star in the + x-direction. Bottom: the red component of the metastable helium triplet is calculated only from the cells that reach a certain threshold in optical depth. These spectra were computed using the full 3D snapshot. The velocity axis is centered around the peak of the red component in the stellar rest frame. This red component comprises two unresolved spectral lines, indicated here by vertical brown lines. Most of the blueshift is contributed by cells with 10⁻³ < Δτ < 10⁻², which corresponds to a line forming region of r ≈ 1–2 R_p.