The Ghost Star is where the spirits of those who fully "pass on" all head off to. It is part of a constellation that is not recognized as part of the thirteen main ones usually found on a Longest Night - thus, it is part of a "lost constellation" (hence the title of the supplemental game itself). The Ghost Star can only be witnessed from the surface of the Frozen Lake, and finding this was the purpose of Adina Astra 's journey through the Forest. Whether she managed to chart it down is unknown, as it is still a "lost" constellation.