The Counterstreaming Instability in Dwarf Elliptical Galaxies with Off-Center Nuclei

n many nucleated dwarf elliptical galaxies (dE,N's), the nucleus is offset bya significant fraction of the scale radius with respect to the center of theouter isophotes. Using a high-resolution N-body simulation, we demonstrate thatthe nucleus can be driven off-center by the m=1 counterstreaming instability,which is strong in flattened stellar systems with zero rotation. The modeldevelops a nuclear offset on the order of 30% of the exponential scale length.We compare our numerical results with the photometry and kinematics of FCC 046,a Fornax Cluster dE,N with a nucleus offset by 1.2" we find good agreementbetween the model and FCC 046. We also discuss mechanisms that may causecounterrotation in dE,N's and conclude that the destruction of box orbits in aninitially triaxial galaxy is the most promising.Comment: 5 pages, 4 figure