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We try to determine the Galactic structure by comparing the observed and modeled velocities of OB-associations in the 3 kpc solar neighborhood. We made N-body simulations with a rotating stellar bar. The galactic disk in our model includes gas and stellar subsystems. The velocities of gas particles averaged over large time intervals ($sim 8$ bar rotation periods) are compared with the observed velocities of the OB-associations. Our models reproduce the directions of the radial and azimuthal components of the observed residual velocities in the Perseus and Sagittarius regions and in the Local system. The mean difference between the model and observed velocities is $Delta V=3.3$ km s$^{-1}$. The optimal value of the solar position angle $theta_b$ providing the best agreement between the model and observed velocities is $theta_b=45pm5^circ$, in good accordance with several recent estimates. The self-gravitating stellar subsystem forms a bar, an outer ring of subclass $R_1$, and slower spiral modes. Their combined gravitational perturbation leads to time-dependent morphology in the gas subsystem, which forms outer rings with elements of the $R_1$- and $R_2$-morphology. The success of N-body simulations in the Local System is likely due to the gravity of the stellar $R_1$-ring, which is omitted in models with analytical bars.
We use N-body simulations to examine whether a characteristic turnaround radius, as predicted from the spherical collapse model in a $rm {Lambda CDM}$ Universe, can be meaningfully identified for galaxy clusters, in the presence of full three-dimensi
We study the dynamics of faint stellar substructures around the Umbrella Galaxy, NGC 4651, which hosts a dramatic system of streams and shells formed through the tidal disruption of a nucleated dwarf elliptical galaxy. We elucidate the basic characte
In the next decade, cosmological surveys will have the statistical power to detect the absolute neutrino mass scale. N-body simulations of large-scale structure formation play a central role in interpreting data from such surveys. Yet these simulatio
The general consensus in the N-body community is that statistical results of an ensemble of collisional N-body simulations are accurate, even though individual simulations are not. A way to test this hypothesis is to make a direct comparison of an en
Stellar tidal streams are sensitive tracers of the properties of the gravitational potential in which they orbit and detailed observations of their density structure can be used to place stringent constraints on fluctuations in the potential caused b