But how make small changes in the trajectory of a star? One idea is to impact the star with large comets. It is not difficult, as remote Oort cloud objects (or wandering small planets, as they are not part of already established orbital movement of the star) need only small perturbations to start falling down on the central star, which could be done via nuclear explosions or smaller impacts by smaller astreoids.
I don’t think this works; conservation of momentum means that the impact is almost fully counteracted by the gravitational pull that accelerated the comet to such speed (so that, in the end, the delta-v imparted to the star is precisely what you imparted with your nuclear explosions or smaller asteroids).
Maybe a Shkadov thruster is what you want? (It’s slow going, though; this article suggests 60ly/200My, accounting for acceleration.)
To solve the “moment problem”, free wandering comets or planets could be used for impacts with a star. There are probably many of them, and they have significant initial radial speeds relative to the star.
I don’t think this works; conservation of momentum means that the impact is almost fully counteracted by the gravitational pull that accelerated the comet to such speed (so that, in the end, the delta-v imparted to the star is precisely what you imparted with your nuclear explosions or smaller asteroids).
Maybe a Shkadov thruster is what you want? (It’s slow going, though; this article suggests 60ly/200My, accounting for acceleration.)
To solve the “moment problem”, free wandering comets or planets could be used for impacts with a star. There are probably many of them, and they have significant initial radial speeds relative to the star.