KINEMATICS OF NGC-4826 - A SLEEPING-BEAUTY GALAXY, NOT AN EVIL EYE

A recent high resolution H I study of the Sab galaxy NGC 4826 [Braun e t al. Nature, 360, 442 (1992)] reveals that the sense of rotation of t he neutral gas reverses from the inner to the outer disk. The present paper reports on optical spectra at high velocity resolution in four p osition angles in NGC 4826, which cover the region of the gas reversal and which reveal a high degree of complexity. In the inner disk, whic h includes the prominent dusty lane, the stars and gas rotate in conce rt, and the spiral arms trail (for the adopted geometry). Arcs of ioni zed gas are observed partially encircling the nucleus; expansion veloc ities reach 400 km/s. At distances just beyond the prominent dust lane , the ionized gas exhibits a rapid, orderly velocity fall and within 5 00 parsecs it has reversed from 180 km/s prograde to 200 km/s retrogra de; it also has a component radial toward the nucleus of over 100 km/s . The stars, however, continue their prograde rotation. Beyond this tr ansition zone, the neutral gas continues its retrograde rotation, stel lar velocities are prograde, but the sense of the almost circular arms is not established. Because of its kinematical complexity as well as its proximity, NGC 4826 is an excellent early-type galaxy in which to observe the long term effects of gas acquisition or a galaxy merger on a disk galaxy.