Stellar orbit

A star’s trajectory through space under the gravitational influence of other bodies. Its shape and motion depend on the masses involved and the star’s position and velocity.

Newtonian gravity: A theory describing gravitational attraction between masses through a force proportional to their product and inversely proportional to distance squared. It supplies the force that governs stellar motion in many systems.
Position vector: A vector specifying an object’s location relative to a chosen origin. A star’s position helps determine its orbit within a chosen reference frame.
Binary star: A pair of stars bound together by gravity and orbiting their common center of mass. Their mutual motion provides a direct setting for measuring stellar orbits.
Hyperbolic trajectory: An unbound path in which an object passes a gravitating body and escapes with nonzero speed at infinity. It contrasts with a bound stellar orbit that repeatedly returns around its gravitating system.
Keplerian orbit: An idealized orbit in which one body moves under the gravity of a single point mass. It approximates a star’s path when one gravitating mass dominates.
Velocity vector: A vector giving an object’s speed and direction of motion. The star’s velocity, together with its position, constrains its future trajectory.
Radial velocity method: A technique that detects motion toward or away from an observer through shifts in spectral lines. Spectral shifts can trace a star’s line-of-sight orbital motion.
Parabolic trajectory: The limiting unbound path with exactly enough energy to escape a point mass and zero speed at infinity. It marks the boundary between bound and unbound two-body motion.
Orbital elements: Parameters that specify an orbit’s size, shape, orientation, and the body’s position along it. They provide a compact description of a stellar orbit.
Mass: A physical property that measures an object’s inertia and contributes to its gravitational influence. The masses of the star and surrounding bodies set the gravitational dynamics.

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