H_\alpha Luminosity and Star Formation of Galaxies in HCGs

Abstract

We have obtained $H_{\alpha}$ fluxes and luminosities for a sample of 95 accordant galaxies from observations of 31 Hickson Compact Groups (HCGs) in the North hemisphere. This sample is the largest $H_{\alpha}$ selected catalogue of galaxies having $H_{\alpha}$ calibrated fluxes so far. The results obtained from a preliminary analysis of a subsample of 66 galaxies show that the $H_{\alpha}$ luminosity of galaxies is correlated with velocity dispersion and compactness of groups. Such correlations would point toward a scenario in which $H_{\alpha}$ brightest galaxies reside in compact groups having higher probability of galaxy interaction i.e. lower values of velocity dispersion. Moreover such relations seem to depend on the environment in which HCGs themselves are embedded.