SIMBAD references

Further optical observations have been made with the Manchester Occulting Mask Imager and Manchester Echelle Spectrometer of the inner and outer shells of P Cygni, and of the 7-arcmin long giant lobe projecting from this luminous blue variable star.

An image in the light of the fluorescently excited [Niii] 7378-Å line has revealed the knottiness of the inner shell. Well defined `velocity ellipses' for the position/velocity arrays across the outer shell indicate that its expansion velocity is 160km.s^–1 which is somewhat lower than the previously reported value.

The kinematical behaviour of the giant lobe, both in the vicinity of P Cygni, and further away, emphasizes its strange nature, although close association with P Cygni is again suggested by these new observations. One possibility is that this lobe is a `trail' of collimated ejected material.

The observations are compared with a 60-µm IRAS high-resolution map of the region.

A variety of possible explanations of the observed phenomena are explored, e.g. radio knots in the outer stellar wind either coalesce or expand to become the [Niii]7378-Å emitting knots in the inner shell; that a mass-loaded wind overunning slower moving clumps explains the kinematics of the inner shell; that the one-sided giant lobe could be a `trail' of ejected material from P Cygni funnelled through the outer shell.