The Molecular Structure of HH 2
We present observations of the molecular region associated with HH 2, in HCO+ J=3-2, NH3 (1,1) and C180 J=2-1. The emission from HCO+ clearly peaks ahead of (SE of) the advancing optical knots that comprise HH 2, though the observed peaks in our NH3 total integrated intensity map are not found to be coincident with the HCO+ peak, and the C180 is distributed throughout the region mapped and shows no clear peak at all. The anti-correlation between the spatial morphologies of each species is thought to be due to the differing excitation requirements of the transitions observed: Whilst the HCO+ shows a dense, quiescent clump ahead of (SE of) HH 2 — identified also in NH3 (1,1) channel maps, the distribution of C180 is more uniform, indicative of a non-changing (on a large-scale) column density of gas over the area mapped. We have not however ruled out the possibility of chemical abundance variations to explain the strong HCO+ /NH3 anticorrelation. Clearly though, the mm and sub-mm lines of HCO+ are the preferred tracers of dense clumping associated with this (and probably other) HHs.
KeywordsColumn Density Dense Clump Bipolar Outflow Spatial Morphology Molecular Clump
Unable to display preview. Download preview PDF.