Shock-excited H[TINF]2[/TINF] Flows in OMC-2 and OMC-3

Abstract

We report the discovery of nearly a dozen collimated outflows from young stellar objects embedded in the molecular filament that extends north of the Orion Nebula towards the H II region NGC 1977. The large number of nearly coeval outflows and embedded class 0 young stellar objects indicates that the OMC-2/3 region is one of the most active sites of ongoing low- to intermediate-mass star formation known. These outflows were identified in the 2.12 μm v = 1-0 S(1) H2 line during a survey of a 6' × 16' region containing the OMC-2 and OMC-3 cloud cores and over a dozen recently discovered class 0 protostars. We also observe filamentary emission that is likely to trace possible fluorescent H2 in photodissociation regions associated with M43 and NGC 1977. Neither the suspected outflows nor the fluorescent emission are seen at the continuum wavelength of 2.14 μm, which confirms their emission-line nature. Several of the new H2 flows are associated with recently discovered bipolar molecular outflows. However, the most prominent bipolar CO outflow from the region (the MMS 8 flow) has no clear H2 counterpart. Several H2 flows consist of chains of knots and compact bow shocks that likely trace highly collimated protostellar jets. Our discovery of more than 80 individual H2-emitting shocks demonstrate that outflows from young stars are churning this molecular cloud.