Extensive, high-speed gas around the Trapezium cluster of the Orion nebula (M 42, NGC 1976).

Very sensitive, spatially resolved observations of forbidden O III 5007-A line profiles have been obtained, with the Manchester echelle spectrometer combined with the Isaac Newton telescope, along one slit length near the Trapezium group of stars in the Orion nebula. The presence of the approaching side of some kind of ionized shell, about 1 arcmin in radius and expanding radially from the cluster at about 100 km/s, is dramatically confirmed, although complexities in the small-scale structure of the outflow demand a complicated explanation. A similarly extensive receding counterpart is not found. Various mechanisms for the creation of this 1 arcmin radius feature are considered.