Evolution and star formation of dwarf galaxies

We currently investigate several samples of dwarf galaxies (BCDs, Irr, dE) by means of a multi-wavlengths study including optical/NIR imaging as well as CO line and 1300 mu m dust continuum observations. Here we present the status of this project and preliminary results: i) From the mm data we find that the metallicity of the cold interstellar medium is normal in Sm types while heavy elements are significantly deficient in Im types. ii) The FIR colours of the various groups indicate that most Sm types have properties like normal giant spirals whereas most Im types resemble large starburst galaxies. iii) The optical and NIR studies corroborate previous suggestions that there are no morphological differences at different wavelengths. iv) The objects in our sample follow the NIR Tully-Fisher relation.