I tried to do this:
placing a star destroyer over a star.
then giving him the command to move to another star.
Then followed the "destroy star" command.
At the target, he said "there is no star", and the other fleet reached him
I lost a whole fleet
do you know if thios a bug or not?
I believe this kind of move only works if you move back to the same star (same goes for planets, and probably wormholes). If you need to go to another system, you will have to keep your ship alive until next turn before giving the order.
Stellar Manipulation orders occur, more or less, right before being able to move to another sector. So a Star Destroyer not moving will destroy the star early on during the turn. I said "more or less" because fleets can sometimes escape the bLast, and sometimes not, all else being equal. (In a 2vs2 game, Slynky and myself polled our wits about this matter, and failed to reach a decisive conclusion)