I also thought I read somewhere that (maybe not merope, but, i think) the pleaides was where the war started with thargs or where thargs first started appearing or something either in an older game or in lore. I am pretty sure I remember reading something about that.
What about Peregrina or similar system? Apparently it was a "plague" system and your ship would be targeted by any faction and marked as a plague ship if you enter the atmosphere. After some digging, someone commented that it is not longer a "plague" system, but they were also waiting for horizions to drop. Seems like something worth investigating.
Looks to me like there are some queues to be taken here guys.....
"The GalCop Navy manages to beat the Thargoid invasion back, a battle line is drawn, centred on sector 9,9. The Thargoids begin sending small reconnaissance fleets behind the battle line and deep into Human territory to survey various systems for later conquest and to raid commercial shipping."
"Massive fleets of Thargoid warships carrying remote controlled fighters ruthlessly cut a swathe into occupied human territory, encroaching on a cluster of stars centered around Alioth"
"Thargoids could be capable of building large artificial structures which could possibly be on a scale with planets" (merope?)
"that attacked critical materials in their hyperdrives, preventing the construction of interstellar vehicles." (possibly part of the meta-alloy thing)
"The Thargoids are also superior in the use of advanced AI and remote craft" (possible UA?)