The trajectories of the two gravitating particles are ellipses, the three interacting particles may already have many different kinds of trajectories. The number of configurations of galaxies consisting of 100 billion stars must be extremely large. Why, morphologically, galaxies are mainly reduced to three types: spiral, elliptical and irregular?
Galaxies that do not experience external influences, over a fairly long time, come to an equilibrium state in which the average speed of stars is constant, and the density decreases from the center to the periphery according to a certain law. The structure of an equilibrium self-gravitating system is determined by three dynamic characteristics: mass, energy and angular momentum.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.