The Earliest Production of Hot Gas in Young Planetary Nebulae

Planetary nebulae (PNe) consist of stellar material ejected by stars with masses<10 solar masses. Both fast stellar winds and collimated outflows contribute tothe shaping of PN shells and fill the shell interiors with shockheated gas attemperatures higher than 10E6 K. XMM and Chandra observations have produced thefirst unambiguous detections of diffuse X ray emission from PNe, but theobserved Xray luminosities of PNe are generally much lower than theoreticalexpectations. Observations of a few young PNe hint at a shortlived phase ofbright X ray emission in early evolutionary stages. We request XMM observationsof 4 very young PNe to further investigate the earliest history and physicalconditions of hot gas produced by fast winds and collimated outflows in PNe. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]