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'', corres
ponding 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 str
ong, narrow emission lines indicating high ionization; their very blue
colors suggest recent bursts of star-formation; their typical luminos
ities are approximately 4 times fainter than that of field galaxies. T
hese characteristics suggest H II galaxies as likely local counterpart
s of our sample, though our most luminous targets appear to be unusual
ly compact for their luminosities.