Evolution of the He I λ5875.66 (D3) line profile of RR Lyr corresponding to the night of August 1, 1996 (ψ = 1.10), within the pulsation phase indicated on the right side. The first D3 line emission is visible between 0.859 ≤ φ ≤ 0.894 and is followed by the P Cygni profile (second D3 emission) between 0.903 ≤ φ ≤ 0.961. The exposure time was 300 s, and the absorption lines beyond 5880 Å are telluric lines. The vertical line represents the D3 line laboratory wavelength. The profiles are presented in the stellar rest frame and are arbitrarily shifted in flux for visibility.