We present narrow-band Hα imaging and long-slit optical and near-infrared spectroscopy of the starburst galaxy NGC 7714. We have detected WR stars in the starburst region, which indicate an age for the burst of between 3 and 5 Myr. We have obtained the physical condition of the gas in the starburst region and in three HII regions. These have moderately low abundances, while the nucleus has half solar abundance, with an overabundance of N.

Introduction

A typical starburst galaxy can be defined as a spiral galaxy with a bright nucleus bluer than expected for its morphological type, which emits strong narrow emission lines similar to low-ionization HII region spectra, as a consecuence of the photoionization by the ultraviolet radiation of hot stars, with typical Hα luminosities ranging from 1040 to 1042 erg s−1. During this intense recent burst of star formation between 107 and 1010 M⊙ of massive stars are formed within a radius of a few hundred pc about its nucleus.

NGC 7714, the prototype of the starburst (henceforth SB) galaxies (Weedman et al, 1981) and classified as a SBb peculiar, is in interaction with the irregular galaxy NGC 7715. The X-ray luminosity (6 1040 erg s−1) is explained with about 104 supernova remmants in a volume of 280 pc radius (Weedman et al. 1981). The 6-cm radio map shows a weak double radio structure separated by about 1 arcsec at p.a = 30°.