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S.-Y. Liu (Astronomy Department, Caltech), J.M. Girart (Universitat de Barcelona), L.E. Snyder, A.J. Remijan (Astronomy Department, UIUC)
We present BIMA Array 1 mm observations of formic acid (HCOOH) emission toward the Orion KL region. HCOOH is the simplest organic acid. Because of its carboxyl group (COOH) which is common to other more complex, biologically interesting molecules, HCOOH is receiving growing attention. Following our previous survey of HCOOH toward hot molecular cores, we carried out 1 mm observations of HCOOH toward Orion KL. With higher S/N and better spatial resolution, we were able to resolve the HCOOH emission structure. Instead of simply being cospatial with the HCOOCH3 emission, as suggested by our results from 3 mm observations at a lower spatial resolution, HCOOH emission is found surrounding the SW edge of HCOOCH3 (as well as (CH3)2O) emission. Its distribution appear to coincide with a region which delineates the boundary between the hot core and the compact region where several H2O masers were observed. This region is suspected to be where outflows from the hot core interact with the ambient quiescent cloud. The chemistry of HCOOH and the implications for other complex interstellar organic species will be discussed.
This research was partially supported by NSF grant AST 99-81546 to Caltech and NSF grant AST 99-81363 to the University of Illinois.