New Herbig-Haro objects and giant outflows in Orion

Abstract

We present the results of a photographic and CCD imaging survey for Herbig-Haro (HH) objects in the L1630 and L1641 giant molecular clouds in Orion. The new HH flows were initially identified from a deep Hα film from the recently commissioned AAO/UKST Hα Survey of the southern sky. Our scanned Hα and broad-band R images highlight both the improved resolution of the Hα survey and the excellent contrast of the Hα flux with respect to the broad-band R. Comparative IVN survey images allow us to distinguish between emission and reflection nebulosity. Our CCD Hα, [S II], continuum and I-band images confirm the presence of a parsec-scale HH flow associated with the Ori I-2 cometary globule, and several parsec-scale strings of HH emission centred on the L1641-N infrared cluster. Several smaller outflows display one-sided jets. Our results indicate that, for declinations south of -6° in L1641, parsec-scale flows appear to be the major force in the large-scale movement of optical dust and molecular gas.