The structure of the Orion nebula

Abstract

The Orion nebula is the best studied of all H II regions. The experimentaldata for this nebula are reviewed, and interpretive models of thestructure of both the nebula and its environs are developed. TheH II region is composed of an inner 3-min core surrounding the excitingstar theta 1 C which is partially imbedded on the near side of amassive neutral complex. A network of strong flows results that resupplieshigh-density ionized gas to the core region. Gas in the core thenfreely expands, where possible, primarily into the foreground, south,and west. Details of this model are compared with optical, radio,and infrared observations of the ionized, neutral atomic, and moleculargas in the Orion nebula. The nature of the neutral complex is alsodiscussed.