In the red, one of the clearest features from massive stars is the CaII triplet. These absorption lines are observed in most starburst galaxies (Terlevich, Díaz, & Terlevich 1990; Storchi-Bergmann, Kinney & Challis 1995; González-Delgado et al 1995) and the spectra of young star clusters (Bica, Alloin & Schmidt 1990; González Delgado et al 1997). These features are very strong in starbursts with ages between 10 and 20 Myr (Mayya 1997; García-Vargas, Mollá, & Bressan 1997) due to the evolution of massive stars to the red supergiant phase. This feature is also detected in a significant fraction of Seyfert galaxies (Terlevich, Díaz, & Terlevich 1990; Nelson & Whittle 1995; González Delgado 1995), and it is as strong as that detected in the central region of normal galaxies (where it is primarily produced by an old population of red giants). The non-dilution of these features points against the interpretation of the spectra of AGN as the sum of the spectra from an old population plus a power law due to the AGN. Otherwise the non-dilution of the CaII triplet can only be explained assuming a cut-off in power law at near-IR wavelengths (Malkan & Filippenko 1983). Therefore, the most natural interpretation is the presence of a starburst population of massive stars.
Of our targets, only NGC 7130 was observed in the red wavelength region. The CaII triplet is clearly detected. The equivalent width of the strongest line (8542 Å) is 3.319#190.4 Å and the weakest one (8498 Å) is 1.4 Å. The line CaII 1#18662 is affected by a bad column in the CCD and its equivalent width is very uncertain. The equivalent width of CaII 1#18542 is comparable to the typical values of this line (3 to 4 Å) in normal early type galaxies (Terlevich, Díaz, & Terlevich 1990).