The Star Tug: An active stellar engine capable of accelerating a star to relativistic velocities

Abstract

Civilizations ahead of our own may wish to control their star system's motion for a variety of reasons, ranging from the avoidance of cataclysmic cosmic events to the facilitation of interstellar, and perhaps intergalactic, colonization. Such an endeavor can be achieved via the construction of megastructures known as stellar engines, which utilize a star's own resources to gradually accelerate the star system in the desired direction over extended periods of time. Here, we conceptualize the ‘Star Tug’, a stellar engine capable of producing significantly higher accelerations than previous stellar engine concepts. The Star Tug consists of an engine positioned ahead of the star along the desired direction of acceleration. The engine is gravitationally bound to the star and utilizes mass acquired from the star as propellant to generate thrust which counterbalances the force of gravity between it and the star. As long as the propellant exhaust velocity exceeds the escape velocity of the star system, the star system should accelerate. Depending on efficiency and engineering constraints, the Star Tug may be capable of accelerating a sun-like star to relativistic velocities within megayear time scales.