Astron. Astrophys. 323, 323-336 (1997)

5. Concluding remarks and summary

With this paper primarily presenting new data, and Paper II containing a discussion of both the optical and radio results, only some concluding remarks will be given.

- A homogeneous set of observations of a sample of H II galaxies through B, R and I filters was obtained. The photometric results consist of integrated magnitudes, surface brightnesses, effective and diameters, and extinction corrected colors at the galaxies' centers and within the aforementioned diameters. Whereas the magnitudes and agree well with previously published data, discrepancies in the effective diameter can be attributed to the strong influence of a galaxy's irregular morphology on the brightness distribution within smaller diameters. The B and R filtered CCD images were used to construct images depicting the colors across the surface of the galaxies.

- Results from flux calibrated H imagery are presented. H fluxes were corrected for extinction and N II -H line blending when possible. Whereas uncorrected H fluxes give lower limits to the thermal radio emission of the galaxies, the corrected H fluxes allow an estimate of the probable thermal radio fluxes, independent from radio measurements. These estimates agree well with thermal radio fluxes derived from actual radio data.

- New radio measurements give nearly complete frequency coverage of the sample galaxies in the range of 0.32 to 15 GHz. The addition of high frequency measurements allows more stringent limits to be set to the thermal emission of some of the galaxies, but did not change significantly DBDKS's interpretation of their radio spectra. The new data allowed to analyze the radio spectra of two additional galaxies in a fashion similar to DBDKS. These spectra, however, did not lend themselves to good fits and an unambiguous interpretation.

- Comparison of the color maps, the radio maps and the H images show that in some galaxies, such as II Zw 40, there is a clear spatial correlation between all indicators of star formation, including radio emission, H II regions and areas of blue stellar colors. Whereas the 1.4 GHz, or 8.44 GHz, radio morphology generally agrees well with the H emission, there is suffient extinction in some galaxies, such as Mkn 297, to obscure the expected blue colors from the star forming regions.

- Despite the fact that the galaxy sample is not particularly rigorously defined, it is interesting to note, that (with the exception of Mkn 527, which does not fit the description of H II galaxies very well) all sample galaxies have been interpreted by at least one author as merging or an interacting systems. The sample galaxies were selected for their strong radio-continuum emission from a larger set of H II galaxies. Possibly, only the relatively short lived merger/interaction events allow for the temporarily increased star formation rates and a correspondingly high radio emission, high enough that they were selected for this study from the much larger pool of H II galaxies.

© European Southern Observatory (ESO) 1997

Online publication: June 5, 1998

helpdesk.link@springer.de