Upper panel: integrated spectra of the S1,S2 and S3 continuum sources. The spectrum of S1 has been de-reddened according to the Balmer decrement in the associated circular region. Lower panel: integrated spectra of the S4, S5 continuum sources. All the spectra are extracted from the circular regions associated with each continuum source and outlined in Fig. 4. The emission lines of the ionized gas have not been masked. Some residuals of the sky subtraction are evident in the red end of the spectra.