Effect of fine-structure splitting (dashed line) and rotational broadening (thick full line) on the emission core of He ii λ 4686 Å (thin full line; strongest emission core). To account for instrumental broadening, all model profiles were convolved with a Gaussian with FWHM = 0.1 Å. The positions of the individual line components are indicated by vertical bars, whose length is proportional to the gf-value. The data gap around 4684 Å stems from incomplete coverage of Echelle orders.