COUNTERROTATING STELLAR DISKS IN EARLY-TYPE SPIRALS - NGC-3593

We report the discovery of two counterrotating stellar disks in the ea rly-type spiral galaxy NGC 3593. The major axis kinematics shows the p resence of two dynamically cold counterrotating components. The surfac e brightness profile is well reproduced by the sum of the contribution s of two exponential disks of different scale lengths (r(1) = 40 ''; r (2) = 10 '') and different central surface brightnesses (mu(r,1) = 19. 9; mu(r,2) = 18.5 mag arcsec(-2)). The nu and sigma radial profiles ar e easily reproduced by the means of a kinematical model adopting the a bove photometric parameters. An ionized gas disk is present. It corota tes with the smaller scale length and less massive (M(2) = 2.7 X 10(9) M(.)) disk, and counterrotates with the larger and more massive (M(1) = 1.2 x 10(10) M(.)) one. We conclude that the smaller stellar disk i s the result of a slow adiabatic acquisition of a conspicuous amount o f counterrotating gas (M(infall) similar to 4.3 x 10(9) M(.)) by the p reexisting galaxy, originally constituted mainly by a aas-free stellar disk (disk 1). The counterrotating gas settled into the equatorial pl ane and then formed the inner stellar disk (disk 2).