The time-series of absorption spectra around the sodium lines for the spot-crossing scenario is shown. The image covers a wavelength interval of 12 Å, centered on the mean position between the two lines. Horizontal black lines indicate the transit contacts: solid black represents T1 and T4, while dashed black denotes T2 and T3 (from negative to positive phase values). At phases corresponding to the spot position, an extra distortion is observed due to the spectral difference between the AR and the stellar photosphere. The sodium lines in the AR appear broader than those in the photosphere, resulting in an apparent emission that extends beyond the distortion near the line core.