A model of spectral galaxy evolution including the effects of nebular emission

¹ Astronomiska observatoriet, Box 515, 75120 Uppsala, Sweden
² Observatoire de Strasbourg, 11 rue de l'Université, 67000 Strasbourg, France

Corresponding author: E. Zackrisson, Erik.Zackrisson@astro.uu.se

Received: 5 July 2000
Accepted: 14 June 2001

Abstract

This paper presents a new spectral evolutionary model of galaxies, properly taking the effects of nebular emission and pre-main sequence evolution into account. The impact of these features in different photometric filters is evaluated, along with the influence that variations in the physical conditions of the gas may have on broadband colours, line ratios and equivalent widths. Inclusion of nebular emission is demonstrated to radically change the predicted ultraviolet, optical and near-infrared colours during active star formation. Pre-main sequence evolution is also seen to give a non-negligible contribution to the luminosity in the near-infrared during the first few million years of evolution and should not be omitted when very young systems are being modelled. Finally, we present a comparison of our predictions to observations and two other recent codes of evolutionary synthesis.