ST ScI Preprint #1382

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

Based on observations obtained at ESO, La Silla, Chile (Observing Programmes 58.A-0192, 59.A-0774, and 61.A-0326), and at the Isaac Newton Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

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 /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.

Status:

Appeared in the proceedings of: New Millennium for Galaxy Morphology, held 13-18 September 1999 in Johannesburg, South Africa

Affiliations:

¹⁾ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218
²⁾ Affiliated with the Astrophysics Division, SSD, European Space Agency
³⁾ Departamento de Astrofisica, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, E-28040 Madrid, Spain
⁴⁾ DAEC-URA173, Observatoire de Paris-Meudon, Place Jules Janssen, Meudon, F-92195, France