Bow-shock fitting of IRS 1W, IRS 5, IRS 10W and IRS 21 in H, K_s and L′ wavelengths. We represent in colors the real image and in contours the best model obtained. The colored vectors represent the velocity of the star (V_s; green arrow), the relative motion of the star through the ISM (V_s−ISM; blue arrow) and the dust motion of the ISM obtained with our bow-shock model (V_ISM; red arrow).