XMM-Newton detection of hot gas in the Eskimo Nebula: Shocked stellar wind or collimated outflows?

Abstract

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^-1, and the existence of a fast bipolar outflow with a line-of-sight expansion velocity approaching 200 km s^-1. 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 ∼2 × 10⁶ K and an X-ray luminosity of L_X = (2.6±1.0) × 10³¹ (d/1150 pc)² erg s^-1, 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.

Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA.