Spectroscopic observations of superthin galaxies.

Spectroscopic observations of the superthin galaxies UGC 4278, 7170, 7321, and 9242 with 4 and 2.1 m telescopes, are reported to demonstrate how the morphology, kinematics and line ratios of a superthin galaxy may be interrelated. Comparisons are also made with two related edge-on systems. The superthin galaxies are characterized by modest central velocity gradients, an underabundance of nitrogen, and very thin disks with little evidence of a central luminosity concentration. The mean H I content is roughly 10% of the estimated match, which is a value close to the mean for late-type Sd spirals, and large-scale galactic shocks may be nonexistent in the disks due to the modest central concentration of mass.