A galaxy that appears as an extraordinary thin and long figure
on the sky because of its → edge-on orientation, highly
flattened stellar → disk,
and absence of a → bulge
component. Superthin galaxies are → gas-rich and have
optically diffuse disks with little internal absorption,
as well as low emission-line intensity ratios and slowly rising
→ rotation curves. They seem to be among the least
evolved disk galaxies in the local Universe, having undergone only minimal
dynamical heating, → star formation,
and → angular momentum transport. Examples are:
UGC 7321, UGC 3697, UGC 9242.
See also: → super-; → thin; → galaxy.
