On the Origin of Planetary Nebula K648 in Globular Cluster M15

We examine two scenarios for formation of the planetary nebula K648: a prompt scenario in which the planetary nebula is ejected and formed immediately after a helium shell flash and a delayed scenario in which a third dredge-up occurs and the envelope is ejected during the following interpulse phase. We present models of both scenarios and find that each can produce K648-like systems. We suggest that the prompt scenario is more favorable but cannot rule out the delayed scenario.