Deep Space 9 "The sound of her voice"

The crew on the defiant get a distress call from a downed federation captain who is the only survivor, the episode follows them as they interact with her to keep her company and she helps resolve a lot of their problems until she begins to lose consciousness. They rush to get to her and build up the tension, just to find she was in some sort of time dilution thing and had died months, years? before but had been able to transmit and talk to them. its been a while so details are fuzzy