HST IMAGES OF VERY COMPACT BLUE GALAXIES AT Z-SIMILAR-TO-0.2

We present the results of HST Wide-Field Camera (WFC) imaging of seven very compact, very blue galaxies with B less-than-or-equal-to 21 and redshifts z approximately 0.1 to 0.35. Based on deconvolved images, we estimate typical half-light diameters of approximately 0.65'', corresponding to approximately 1.4 h-1 kpc at redshifts z approximately 0.2. The average rest frame surface brightness within this diameter is mu(V) approximately 20.5 mag arcsec-2, approximately 1 mag brighter than that of typical late-type blue galaxies. Ground-based spectra show strong, narrow emission lines indicating high ionization; their very blue colors suggest recent bursts of star-formation; their typical luminosities are approximately 4 times fainter than that of field galaxies. These characteristics suggest H II galaxies as likely local counterparts of our sample, though our most luminous targets appear to be unusually compact for their luminosities.