The source's tangential arrows respectively point along and against the original motion; point radially outward and inward. Write for the initial orbital radius, for the circular orbital speed, and for the small added speed. The resulting trajectories follow the velocity kick on a circular Kepler orbit formulas. Here orbital energy includes kinetic energy and gravitational potential energy; angular momentum refers to the central object.
Four Kepler orbits following small tangential or radial velocity changes
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