XMM-Newton Detection of Hot Gas in the Eskimo Nebula: Shocked Stellar Wind or Collimated Outflows?

The Eskimo Nebula (NGC 2392) is a double-shell planetary nebula (PN) known for the exceptionally large expansion velocity of its inner shell, ~90 km/s, and the existence of a fast bipolar outflow with a line-of-sight expansion velocity approaching 200 km/s. We have obtained XMM-Newton observations of the Eskimo and detected diffuse X-ray emission within its inner shell. The X-ray spectra suggest thin plasma emission with a temperature of ~2x10^6 K and an X-ray luminosity of L_X = (2.6+/-1.0)x10^31 (d/1150 pc)^2 ergs/s, where d is the distance in parsecs. The diffuse X-ray emission shows noticeably different spatial distributions between the 0.2-0.65 keV and 0.65-2.0 keV bands. High-resolution X-ray images of the Eskimo are needed to determine whether its diffuse X-ray emission originates from shocked fast wind or bipolar outflows.Comment: 4 pages, 2 figures, accepted in Astronomy and Astrophysics Letter