Equivalent width Measurements in Optical Spectra of Galaxies in Local Clusters: Hints On the Star Formation History in Clusters

Abstract

Equivalent widths of spectral lines in the optical spectra of galaxies are commonly used to characterize their stellar populations and to get some insight on their evolution. Here we describe a new method to measure automatically equivalent widths of spectral lines with a good accuracy. This makes possible to classify galaxies according to the presence/absence and intensity of [O II] and Hδ lines. Based on these classification criteria, we give a description of the characteristics of the star-forming and post-starburst galaxies in local clusters, and their dependence on the cluster characteristics.

Keywords

• galaxies
• classification
• starburst
• clusters