Fourier transforms of synthetic line profiles with positions of the first zero indicated with vertical dotted lines. Left panel: ν sin i parameter is varied from 42 km s⁻¹ (blue) to 90 km s⁻¹ (black) with a step of 6 km s⁻¹ (grey). Middle panel: Linear limb darkening coefficient e is varied from 0.2 (black) to 1.0 (light grey), while ν sin i is kept fixed at 50 km s⁻¹. Right panel: A different contribution of the macroturbulence Θ to the total line broadening is assumed: Θ/v sin i = 0.3, 0.6, 1.2 and 1.8, with ν sin i fixed to 50 km s⁻¹. The inset is a zoom onto the region of the position of the first zero.