Direct Evidence for a Bipolar Stellar Wind in NGC 2392

Abstract

Very high spectral resolution slit spectra have been used to investigate the kinematic structure of the double shell planetary nebula NGC 2392, the Eskimo Nebula. Each shell produces a spectrum corresponding to the projected radial velocity, a pattern which varies according to the position angle of the spectrograph's entrance slit. Multiple slit observations were used to determine that the inner shell is an incomplete prolate spheroid pointed almost at the observer and missing the tip ends. The outer shell is nearly spherical and more uniform.