Yeah, ur best bet is the largest maps: the huge multi system random map - with 102 Grav wells (5 stars), Hyperion's Gates - with 72 Grav wells (3 stars), or maybe Implosion, a single system with 65 wells.
Ancient Gifts with 101 wells, is mostly wormholes (35! & 14 stars!), and each homeworld recieves the jump drive artifact only.
Tip (Cheat): Save, Surrender, Keep Playing, see all artifact locations, count to see if there are 9 or more, Reload, and colonize/explore those.