THE CIRCUMNUCLEAR RING OF IONIZED-GAS IN NGC-3593

We present the results of narrow-band H alpha+[N II] imaging of the ea rly-type spiral NGC 3593 in combination with a study of the flux radia l profiles of the [N II] (lambda lambda 654.80, 658.34 nm), H alpha, a nd [S II] (lambda lambda 671.65, 673.08 nm) emission lines along its m ajor axis. The galaxy is known to contain two counterrotating stellar discs of different size and luminosity. We find that the Her emission mainly derives from a small central region of 57 '' x 25 ''. It consis ts of a filamentary pattern with a central ring. This has a diameter o f about 17 '' (similar to 0.6 h(-1) kpc) and it contributes about half of the total H alpha flux. The ring is interpreted as the result of t he interaction between the acquired retrograde gas which later formed the smaller counterrotating stellar disc and the pre-existing prograde gas of the galaxy.