You can also escape by landing your starship in the hangar of a freighter. It doesn’t have to be your own freighter either. You can also reach the safety of the space station if it is close by. I think I also managed to escape by twisting and turning through metorites breaking their line of sight. Or at least I used to be able to.
I think it also possible to quickly call your freighter into existence before any warning countdown ends, between finishing off the last attacking sentinel and before the next one spawns. Then you have somewhere safe to land on.
Also make use of carrying some defence chits. Then you can call on friendly help to keep them busy while you escape.
I wonder if it is possible to outrun them with upgraded S-class engines or at least until they give up? 
One thing I have discovered is that fighting the sentinels will reward you with the parts needed for upgrades on any Fleet you have built. Like the Quad Servos for example to speed up missions etc. Lots of other lucrative rewards too so it isn’t all bad news if they are on your tail…
