The relative efficiencies of bars and clumps in driving disc stars to retrograde motion

The presence of stars on retrograde orbits in disc galaxies is usually attributed to accretion events, both via direct accretion, as well through the heating stars. Recent studies have shown that can also be produced scattering by dense clumps, which are often present early stages a galaxy's evolution. However, so far it has been unclear whether other internally-driven mechanisms, such bars, capable driving motion. Therefore, this paper, we investigate efficiencies with bars and clumps produce galaxies. We do comparing fractions spatial distributions populations four $N$-body$+$smooth particle hydrodynamics (SPH) simulations isolated spanning range evolutionary behaviours. find generating significant order $\sim 10\%$ all while clump-driven may found at large galactocentric radii, bar-driven remain vicinity bar, even if bar dissolves. Consequently, Solar Neighbourhood clumpy models exclusively clump-driven, but trace population, constituting $0.01-0.04\%$ total stellar population region. Finally, neither (including dissolving ones) nor able rotationally supported counter-rotating discs.