To be honest, I'm kind of surprised nobody has suggested this already (or if they have, I haven't seen it). I think it would greatly add to the mystique of the game if some systems orbited around huge black holes instead of stars. When traveled into, the player would be transported into some sort of special sector for a short amount of time. In this sector, the coordinates would simply show up as "???" and the only way to escape the sector would be to enter a specific set of coordinates (or just click another sector's button). Once left, the black hole sector could never be returned to. Not sure what would be in these special black hole dimensions, but I think it would be pretty cool nonetheless.
Maybe there could be ruined ships or just nothing at all. And your ship could get damaged by going in one.
I think you should look up what a black hole really is. Otherwise you'd be flying your ship to it's own demise!
I know what a black hole is. I'm saying for the purpose of the game. And if not a black hole leading to pocket sectors then maybe a wormhole.