STAR-FORMATION HISTORIES IN H-II GALAXIES .1. OPTICAL AND RADIO OBSERVATIONS

In this paper we report CCD photometry in broad band B, R, and I color s, as well as in the Her, for a sample of eight H II galaxies with str ong radio emission. In addition, we present new radio continuum observ ations in the frequency range between 8 and 15 GHz. For seven of these galaxies, previous radio continuum observations have been reported by Deeg et al. (1993); data on Hare 1 are presented here for the first t ime. Their unusual radio spectra, according to Deeg et al., are a cons equence of rapidly changing star formation rates in their past. An ind ependent verification of this conclusion is the motivation for the opt ical observations reported here. Their interpretation is the subject o f the next article in this series. The new radio measurements confirm the interpretation of the radio spectra by Deeg et al. In combination with extinction corrected Her fluxes, the new radio measurements allow the determination of thermal radio fluxes - a fundamental parameter f or star formation rates with higher reliability than is possible from one wavelength domain alone. Overlays of optical observations at diffe rent colors with radio maps, as well as a search of the literature, in dicates that all sample galaxies are in interacting environments, whic h is a possible prerequisite for the strength of the radio emission an d star formation observed in these galaxies.