The structure and stability of orbits in Hoag-like ring systems

Understand

Ring galaxies are amazing objects exemplified by the famous case of the Hoag's Object.

• Here the mass of the central galaxy may be comparable to the mass of the ring, making it a difficult case to model mechanically.
• In a previous paper, it was shown that the outer potential of a torus (ring) can be represented with good accuracy by the potential of a massive circle with the same mass.
• This approach allows us to simplify the problem of the particle motion in the gravitational field of a torus associated with a central mass by replacing the torus with a massive circle.