STRUCTURAL DETAILS OF THE ORION NEBULA - DETECTION OF A NETWORK OF STRINGLIKE IONIZED FEATURES

We present high-resolution (1″.8 × 1″.6) radio continuum images of the Orion Nebula at 20 cm based on measurements made with the VLA in a number of its configurations. The overall morphology of ionized gas at 20 cm wavelength shows a number of striking new substructures associated with this geometrically complex H II region. On the largest scale, we find a number of linear features, which are considered as new ionization fronts, and which form a 40° angle with respect to the main ionization front known as the "bar" in M42. These features together with the ridge of emission from the optical bar form a conelike appearance whose 5′-10′ envelope is centered near the Trapezium cluster. On a small scale, we report the detection of a web of stringlike features with typical widths of a few arcseconds (≈ 1016 cm) which are concentrated throughout the Trapezium region. These features reveal morphological evidence for production of shocked ionized gas in starforming regions, perhaps driven by powerful winds from mass-losing stars and/or by the shock fronts produced at the edge of expanding H II regions.