Deadhead
Deadheading is travelling towards a star system at the speed of light under the power of conventional engines.
It is commonly the only way for low TL empires to get to distant stars when the wormhole routes are undiscovered or too dangerous and they haven't discovered Warp Drive technology yet.
If a ship without a player or Officer on board tries to leave a system though, they will collide with Dark Matter.
Travelling to a star system can take anywhere from an hour to several hours.