Observations of spatial and velocity structure in the Orion molecular cloud ^*,**

¹ Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C, Denmark e-mail: dfield@phys.au.dk
² Observatoire de Paris and Université de Cergy-Pontoise, LERMA and UMR 8112 du CNRS, 92195 Meudon, France
³ Observatoire de Paris-Meudon, LESIA, 92195 Meudon Principal Cedex, France

Received: 5 October 2005
Accepted: 15 December 2006

Abstract

Observations are reported of H₂ IR emission in the S(1) line at 2.121 μm in the Orion Molecular Cloud, OMC1, using the GriF instrument on the Canada-France-Hawaii Telescope. GriF uses a combination of adaptive optics and Fabry-Perot interferometry, yielding a spatial resolution of 0.15´´ to 0.18´´ and velocity discrimination as high as 1 km s^-1. 193 bright H₂ emission regions can be identified in OMC1. The general characteristics of these features are described in terms of radial velocities, brightness and spatial displacement of maxima of velocity and brightness, the latter to yield the orientation of flows in the plane of the sky. Strong spatial correlation between velocity and bright H₂ emission is found and serves to identify many features as shocks. Important results are: (i) velocities of the excited gas illustrate the presence of a zone to the south of BN-IRc2 and Peak 1, and the west of Peak 2, where there is a powerful blue-shifted outflow with an average velocity of -18 km s^-1. This is shown to be the NIR counterpart of an outflow previously identified in the radio, originating from either source I or source n. (ii) There is a band of weak radial velocity features (<5 km s^-1) in Peak 1. (iii) A small proportion of the flows may represent sites of low mass star formation and one region shows evidence of multiple flows which may indicate multiple low mass star formation within OMC1.