Constraining age and metallicity of bulges embedded in low surface brightness galaxies

We present results from deep Magellan and VLT long slit optical spectroscopy for a sample of 19 face-on low surface brightness galaxies (LSBGs) selected from the sample of Galaz et al. (2002). In particular, we compute Lick/IDS indices for the light emitted by the bulges hosted by these galaxies. Similar procedure is performed for a sample of 14 face-on high surface brightness sample from the sample of Peletier & Balcells (1996). Results indicate that bulges of LSBGs are metal poorer, compared to those hosted by HSBGs, supporting the hypothesis that stellar formation rates have been stable low during the lifetime of these galaxies. We compare our results with those of Bergmann, Jorgensen & Hill (2003).