Highly supersonic motions within the outer features of the η Carinae nebulosity

Spatially resolved H$\alpha$ and [N{\sc ii}] line profiles have been obtainedover striking features in the outer regions of the Eta Carinae nebula. Thehighly irregular outer `shell' of low ionization, [N{\sc ii}] bright, knots hasbeen shown to exhibit radial velocities between -1200 and +300 km/s withrespect to the systemic radial velocity, over its perimeter. Furthermore,several knots have been found which appear to emit only in the H$\alpha$ linewith radial velocities up to -1450 km/s. However, the most intriguing features are a narrow `spike' that projectsthrough this outer shell and a faint `arc' of emission that extends well beyondit. The `spike', which exhibits a change of radial velocity along its length,could be a narrow collimated jet with an outflow velocity of > 1000 km/s. Inone interpretation the `arc' is modelled by a conical outflow and mechanismsfor generating [N{\sc ii}] emission from highly supersonic gas are alsodiscussed.