Definition
A stellar system is an astronomical structure consisting of a central star and a collection of celestial bodies orbiting it. These include planets, moons, asteroids, comets, dust, and sometimes debris disks. Everything is bound together by the gravitational force of the main star.
Structure
The structure of a stellar system is organized by distance from the star: rocky planets are usually closer, followed by gas giants, then more distant asteroid or comet belts. Some planets have moons, and circumstellar disks may surround the star during early system phases. The gravitational center is occupied by the star, around which all other elements are arranged.
Gravitational Functioning
The stellar system is based on gravitational interactions among the bodies. The star dominates the dynamic motion, keeping other objects in their orbital paths. Planets influence their satellites and surrounding smaller objects. The balance of these interactions enables the system's long-term stability.
Evolution
A stellar system forms from a cloud of gas and dust collapsing under its own gravity, forming a protostar surrounded by a protoplanetary disk. Orbital bodies gradually form through accretion. The system evolves over time: planetary migration, material loss, dynamic interactions, or external disturbances can change its structure. In the final stage, the star’s evolution affects the entire system's configuration.
Variation and Limits
Stellar systems vary in star type, number of planets, arrangement, and presence or absence of zones or disks. Some systems have multiple stars (binary or multiple systems) with distinct dynamic configurations. The boundaries of a stellar system are determined by the star’s gravitational influence, called the Hill sphere.