Old Stellar Populations. VI. Absorption-Line Spectra of Galaxy Nuclei and Globular Clusters

Abstract

We present absorption-line strengths on the Lick/IDS line-strength system of 381 galaxies and 38 globular clusters in the 4000--6400 à region. All galaxies were observed at Lick Observatory between 1972 and 1984 with the Cassegrain Image Dissector Scanner spectrograph, making this study one of the largest homogeneous collections of galaxy spectral line data to date. We also present a catalogue of nuclear velocity dispersions used to correct the absorption-line strengths onto the stellar Lick/IDS system. Extensive discussion of both random and systematic errors of the Lick/IDS system is provided. Indices are seen to fall into three families: α-element-like indices (including CN, Mg, Na D, and TiO_2) that correlate positively with velocity dispersion; Fe-like indices (including Ca, the G band, TiO_1, and all Fe indices) that correlate only weakly with velocity dispersion and the αindices; and Hβwhich anti-correlates with both velocity dispersion and the αindices. C_2 4668 seems to be intermediate between the αand Fe groups. These groupings probably represent different element abundance families with different nucleosynthesis histories.

44 pages, including 14 embedded .eps figures plus 4 external tables. Accepted to the Astrophysical Journal Supplement Series, May 1998. ASCII format data for tables are available at ftp://ftp.ucolick.org/pub/users/sctrager/galaxies/ids/tables/ and FITS spectra are available on request from the first author