Surface photometry of bulge dominated low surface brightness galaxies

We present results of broad band BVRI observations of a sample of galaxies with a low surface brightness (LSB) disk and a bulge. These galaxies are we ll described as exponential disks and exponential bulges with no preferred value for either scale length or central surface brightness. The median B b and disk scale length is 12.6 kpc (H-0 = 75 km s(-1) Mpc(-1)) which is much larger than scale lengths of typical (disk dominated) LSB or high surface brightness (HSB) galaxies. Furthermore, the disk and bulge scale lengths ar e correlated, suggesting a coupling in the formation. Bulge dominated LSB g alaxies are observed to be redder than disk dominated LSB galaxies and thei r bulge-to-disk ratios are increasing towards redder wavelengths. We find c olors that are comparable to or bluer than HSB galaxies of the same morphol ogical types. Bulge dominated LSB galaxies are therefore not faded HSB gala xies with no current star formation. We find that bulge dominated LSB galax ies fit in with the general trends defined by the HSB galaxies. The propert ies of these bulge dominated LSB galaxies show that LSB galaxies do not jus t come in two varieties. They cover the entire range in optical and morphol ogical properties between late-type disk dominated LSBs and giant Malin-1-l ike LSBs. LSB galaxies thus also form a LSB Hubble sequence, parallel to th e classical HSB one.