A Shkadov thruster is a hypothetical device built by a Type II Kardashev civilization to control a star's motion. It consists of a mirror of rim angle psi placed at some distance r from a star S (see figure). The mirror causes an asymmetry of stellar radiation in the star-mirror system and, consequently, gives rise to a net thrust on the star. For a certain mirror of superficial mass density, a balance exists between the gravitational force and the force due to star radiation pressure and the mirror-star distance remains constant. It can be shown that, for a well-designed system, the thrust could produce a significant deviation of the Solar System's normal trajectory in the Galaxy.¹

 

Reference

1. Shkadov, L. M. "Possibility of controlling solar system motion in the galaxy," 38th Congress of IAF," October 10-17, 1987, Brighton, UK, paper IAA-87-613.