Fitting Voigt profiles in the wavelength range around the He I IR triplet (10 829–10 835 Å). Three models (solid blue lines) at different states of activity are shown: a model with He I IR in absorption (top panel,number 042 from Hintz et al. 2019 or number A2 from the model series A, details are given in Sect. 2.4), one nearly filled in (middle panel, number 149), and one with the line in emission (bottom panel, number 121). The red dashed line is the best fit of four Voigt profiles in the wavelength range of 10 829–10 835 Å. The dashed green line represents the single Voigt profile fit to the center of the two indistinguishable red components of the He I IR triplet at 10 833.25 Å (dashed vertical line). The pEW of the He I IR line is calculated from the green Voigt profile.