The first true interstellar rocket ships the Branan built mounted disposable rocket engines that could perform a steady burn at one of their standard gravities for a few of our months. That was enough to accelerate up to nearly five percent the speed of light, which is real speed on an interstellar scale. The closest binary star system to Betelgeuse was only a couple decades away at that speed. They would turn around after their first burn period and use the depleted rockets as a meteorite shield during the decades long trip across interstellar space. Then they detached the rockets, engaged their own internal engines, and decelerated back down to match speeds with the local stars and their planetary systems. Improvements in fuel efficiency over the decades and centuries that followed allowed them to accelerate for longer periods of time until they could finally achieve one tenth the speed of light. Even their furthest star was only three decades away from home at that speed. Only. It was a good thing that the crew and passengers slept most of the way.