ESPaDOnS spectrum of BD+40 4220 (black line) and a simulation of the data (green line) based on a flat continuum, a convolved synthetic atmospheric water vapor profile, two Gaussian profiles representing the 9402.5and 9424.5 Å N III emission lines (violet lines), two Gaussian absorption profiles representing the two 9412 and 9428 Å DIBs present in the spectral region (red lines), a broad stellar absorption line at ~9443 Å (pink line). The stellar emission lines have been Doppler shifted in agreement with the results shown in Fig. 5. The green dashed line is the same adjustment without the 9428 Å DIB.