Lower panel: GRAVITY spectrum from 2.0 μm to 2.2 μm (blue-solid line) with a vertical scale that displays the complete line profiles. Upper panel: magnification of the GRAVITY spectrum, where the fine details of our best-fit model (red-dashed line) and of the reference spectrum derived with the stellar parameters from Groh et al. (2012a) (black-dashed line) are appreciated. Notice that the He I 2s-2p and He I 3p-4s are only matched by our hotter red model.