Best fit of the He I 5876 line in ES 21.1 with two different models. Both models use three Gaussian functions. In the left panel, the Gaussian for the NC is symmetric, while in the right panel it has two different σ. See Appendix B for details on the model. The single components are marked with dashed lines, with the blue one indicating the Gaussian for the NC. The insets are a zoom on the NC.