IANAP and this could be a bit of a stretch, but could the disappearance of the star been caused by the completion of a Dyson sphere around it?
Edit: AFAIK, this group didn't look for that. But the fact that nobody ever found one is telling.
However, I absolutely love the Night's Dawn Trilogy and re-read it once every few years. I think I read it at an impressionable age and it really stuck.
One could also consider reading Charles Stross' "Accelerando" which has plenty of stuff about dyson swarms.
For more Peter F Hamilton optimistic future of humanity, see the Night's Dawn trilogy.