Shkadov thruster

The Shkadov thruster is a Class A stellar engine that accelerates a star by selectively reflecting or absorbing light on one side of the star's surface. This could be used to move our own sun out of the way of danger, or move a rogue star away from damaging our solar system, preventing an ELE.

Detail:
Such an engine is a stellar propulsion system, consisting of an enormous mirror/light sail which is a massive type of solar statite (from the words static and satellite) which is an artificial satellite that employs a solar sail to continuously modify its orbit in ways that gravity alone would not allow. This would balance gravitational attraction towards and radiation pressure away from the star. Since the radiation pressure of the star would now be asymmetrical, i.e. more radiation is being emitted in one direction as compared to another, the 'excess' radiation pressure acts as net thrust, accelerating the star in the direction of the hovering statite. Such thrust and acceleration would be very slight, but such a system could be stable for millennia. Any planetary system attached to the star would be 'dragged' along by its parent star. For a star such as the Sun, with luminosity 3.85 × 1026 W and mass 1.99 × 1030 kg, the total thrust produced by reflecting half of the solar output would be 1.28 × 1018 N. After a period of one million years this would yield an imparted speed of 20 m/s, with a displacement from the original position of 0.03 light-years. After one billion years, the speed would be 20 km/s and the displacement 34,000 light-years, a little over a third of the estimated width of the Milky Way galaxy.