Mysteries and Discoveries from the Chandra Planetary Nebulae Suvery (ChanPlaNS)

Chandra observations of planetary nebulae (PNe) have ushered in a new wave of discoveries and mysteries in this class of evolved stars. The X-ray emission from PNe comes in two flavors: compact sources in the vicinity of the central star and extended sources that fill the nebular cavities generated during the PN formation process. The latter variety, called hot bubbles, are chemically-enriched with helium shell burning products (C, O, and Ne) and their temperatures seem to be regulated by heat conduction across the bubble-nebula interface or by charge-exchange with "pickup ions" within the bubble. Perhaps more exotic are the compact sources at PN central stars. The (relatively hard) X-ray spectral energy distributions of all but one of these point sources cannot be explained by blackbody-like emission from the hot central stars but, instead, suggest the presence of even hotter thermal plasmas. The origin of this plasma emission may be coronae of binary companions, NLTE photospheric emission from the central (proto) white dwarfs, low-level accretion, or shocks in the chemically-enriched stellar wind. We are uncovering and investigating all of these phenomena via the Chandra Planetary Nebulae Survey (ChanPlaNS), a volume-limited archival and multi-cycle survey of planetary nebulae in the solar neighborhood. I present the highlights from our analysis and results and the promising prospects afforded by ChanPlaNS.