Optical/near-IR surface photometry of blue low surface brightness galaxies

We present luminosity profiles, colour profiles and disk parameters based o n near-infrared JHK surface photometry of a sample of blue low surface brig htness galaxies (BLSBGs). The results are discussed along with previously o btained optical data. We find that the morphological properties in optical and near-IR are quite similar. The luminosity profiles have exponential sha pes modified by a small central bulge or, below mu(B,0) similar to 23 magni tudes arcsec(-2), a trough. The blue LSBGs have scalelengths intermediate b etween normal LSB disks and gas rich dwarf galaxies. A correlation between scalelength and B-V colour is found for LSBGs in general. In comparison wit h normal late type disk galaxies our galaxies are bluer and smaller. At the same B scalelength, the two types differ in luminosity with 2 magnitudes, corresponding to a difference in mean star formation rate of a factor 5-10. Several photometric properties indicate that they contain very little dust and that, at the lowest surface brightnesses, the stellar population is ho mogeneous.