New means of interstellar travel are now being considered by various research teams , assuming lightweight spaceships to be accelerated via either laser or solar radiation to a significant fraction of the speed of light ( c ) .
We recently showed that gravitational assists can be combined with the stellar photon pressure to decelerate an incoming lightsail from Earth and fling it around a star or bring it to rest .
Here , we demonstrate that photogravitational assists are more effective when the star is used as a bumper ( i.e .
the sail passes “ in front of ” the star ) rather than as a catapult ( i.e .
the sail passes “ behind ” or “ around ” the star ) .
This increases the maximum deceleration at \alpha Cen A and B and reduces the travel time of a nominal graphene-class sail ( mass-to-surface ratio 8.6 \times 10 ^ { -4 } { gram m } ^ { -2 } ) from 95 to 75 yr .
The maximum possible velocity reduction upon arrival depends on the required deflection angle from \alpha Cen A to B and therefore on the binary ’ s orbital phase .
Here , we calculate the variation of the minimum travel times from Earth into a bound orbit around Proxima for the next 300 yr and then extend our calculations to roughly 22,000 stars within about 300 ly .
Although \alpha Cen is the most nearby star system , we find that Sirius A offers the shortest possible travel times into a bound orbit : 69 yr assuming 12.5 % c can be obtained at departure from the solar system .
Sirius A thus offers the opportunity of flyby exploration plus deceleration into a bound orbit of the companion white dwarf after relatively short times of interstellar travel .