Nearby early-type galaxies with ionized gas.II. Line-strength indices for 18 additional galaxies

TL;DR

This paper expands the dataset of line-strength indices for early-type galaxies, providing measurements for 18 additional galaxies and comparing these with existing literature to enhance understanding of galaxy properties.

Contribution

It introduces new line-strength index measurements for 18 early-type galaxies, supplementing previous data and enabling better analysis of galaxy characteristics.

Findings

Expanded dataset of 18 galaxies with line-strength indices

Comparison with literature data to validate measurements

Enhanced understanding of galaxy stellar populations

Abstract

Rampazzo et al. 2005 (Paper I) presented a data-set of line-strength indices for 50 early-type galaxies in the nearby Universe. The galaxy sample is biased toward galaxies showing emission lines, located in environments corresponding to a broad range of local galaxy densities, although predominantly in low density environments. The present addendum to Paper I enlarges the above data-set of line-strength indices by analyzing 18 additional early-type galaxies (three galaxies, namely NGC 3607, NGC 5077 and NGC 5898 have been already presented in the previous set). As in Paper I, we measured 25 line-strength indices, defined by the Lick IDS "standard" system (Trager et al. 1998; Worthey & Ottaviani 1997), for 7 luminosity weighted apertures and 4 gradients of each galaxy. This paper presents the line-strength data-set and compares it with the available data in the literature.