What type of celestial structure is characterized by the orbit of small particles around a star?

The correct answer identifies an accretion disc as a structure where small particles orbit around a star. An accretion disc forms from material, such as dust and gas, that is attracted to a central mass due to gravitational forces. As this material spirals inward, it can often take on a disc shape around the star, with particles orbiting in a stable manner. This concept is particularly relevant in scenarios involving the formation of stars and planetary systems, as well as in the dynamics of certain astronomical phenomena, such as black holes or young star systems.

An asteroid belt, while also composed of small objects, is a region located between planets in a solar system and involves a collection of larger asteroids rather than a dense ring of particles actively involved in a disc-like motion around a star. A nebula represents a vast cloud of gas and dust in space but does not specifically denote the organization of small particles around a star in an orbital configuration. A galaxy encompasses a massive assemblage of stars, star systems, and possibly various types of celestial bodies, but it does not specifically refer to the context of small particles in stable orbits around a singular star.