Had a hyperdiction yesterday evening. Three Thargoid ships, two turned to scan me while the third sped off and jumped out. The other two just held position with my ship and I could only change my distance from them by boosting to around 350. I spent over half and hour with the two, photographing them (see further back in the thread). Honking, flashing lights, jetisonning and sending over refuel limpets had no effect (not really surprised). Ultimately ramming them turned them hostile. At this point they go red and deploy a circling cloud of Thargons. By retreating it does seem possible to hold them in this formation ..
http://i.imgur.com/n4dmgRs.jpg
.. but ultimately the Thargons then speed up their circling until they're a spinning blur around the main ship and then they come at you. To be honest the damage they deal at this point was nowhere near as bad as I expected and there was plenty of time to escape mass lock and jump back into SC.
Terrific experience only marred by a few quibbles ..
1) Don't know if it was bugged but the fact they sit there indefinitely seems a bit naff.
2) I'm gonna get really sick of the Thargoid aggressive encounter (drumming) music, it's the first time that I've felt that the ED music was not up to scratch.
3) The way the Thargoid ships held position with mine was totally unrealistic - they basically responded directly to my thruster inputs, if I thrust left they move left, thrust up and they move up ... not reacting (with a realistic reaction time delay) to the movements of my ship, but directly to my own control inputs.