Line Strengths and Line Strength Gradients in Bulges along the Hubble Sequence

Abstract

We present first results of a comprehensive survey of deep long-slit spectra along the minor axis of bulges of edge-on spiral galaxies. Our results indicate that stellar populations in bulges are fairly old and encompass a range of metallicities. The luminosity-weighted ages of bulges range from those found for cluster ellipticals to slightly ``younger'' (by up to only a few Gyr, however). Their $\alpha$/Fe element ratio is typically supersolar, consistent with those found in giant ellipticals. The radial line-strength gradients in bulges correlate with bulge luminosity. Generally, these findings are more compatible with predictions of the ``dissipative collapse'' model than with those of the ``secular evolution'' model.