High-resolution, co-added and normalised UVES spectrum of OGLE-417 (in black) of the temperature-sensitive H_α (left) and H_β (right) lines. Four models from Kurucz (1993) of the Balmer line profile for T_eff, of 3500 K (magenta), 4500 K (red), 5500 K (green), and 6500 K (blue) are also displayed. The red wing of the H_α line has an asymmetric shape due to the presence of the source star. The contrast between the foreground and source star is higher in the blue (see Fig. 2). Thus, the contribution from the source is lower for the H_β line.