Top: mean in-transit absorption spectra in the planetary rest frame around the Na I D1 line. Bottom: spot contribution as the difference obtained by subtracting the quiet-star profiles from the star with a spot profiles. Each column represents (from left to right) the impact of spot size, spot position (longitude and latitude, respectively), and stellar rotational velocity. In each case the fixed parameters were f_sp = 1%, θ_lat = 25°, θ_lon = 20°, and v sin i = 2 km s⁻¹.