HIGHLY SUPERSONIC MOTIONS WITHIN THE OUTER FEATURES OF THE ETA-CARINAE NEBULOSITY

Spatially resolved H alpha and [N II] line profiles have been obtained over striking features in the outer regions of the eta Carinae nebula . The highly irregular outer 'shell' of low-ionization, [N II]-bright, knots is shown to exhibit radial velocities between -1200 and + 300 k m s(-1) with respect to the systemic radial velocity, over its perimet er. Furthermore, several knots are found which appear to emit only in the H alpha line with radial velocities up to -1450 km s(-1). However, the most intriguing features are a narrow 'spike' that projects throu gh this outer shell, and a faint 'arc' of emission that extends well b eyond it. The 'spike', which exhibits a change of radial velocity alon g its length, could be a narrow collimated jet with an outflow velocit y of greater than or equal to 1000 km s(-1). In one interpretation the 'arc' is modelled by a conical outflow, and mechanisms for generating [N II] emission from highly supersonic gas are also discussed.