Optical studies of HI-rich southern galaxies. II. The low- visibility spiral NGC 1079.

NGC 1079 is an unusual early-type barred spiral galaxy. It differs from normal systems in three aspects: (1) its H I content per unit blue luminosity is three times too high, (2) the rotation velocity and thus the inferred mass are approximately twice as large as in normal galaxies with similar luminosities, and (3) the optical structure is peculiar with low surface brightness spiral arms occurring exterior to an old-population-dominated, high surface brightness center. The authors suggest that these features can be understood if NGC 1079 is a galaxy which is deficient in luminous matter (stars and gas) relative to its dynamical mass within the Holmberg radius.