BIMA Observations of the VLA 1623 Molecular Outflow

Abstract

We present 12CO J = 1-0 and H13CO+ J = 1-0 observations of the spectacular VLA 1623 outflow that were obtained with the Berkeley-Illinois-Maryland Association (BIMA) interferometer at resolutions of 123 × 44 and 97 × 69, respectively. The 12CO outflow image reveals a clumpy, nonlinear morphology akin to optical jet outflows and Herbig-Haro objects. We identify partially unresolved CO clumps labeled A through H, of which only A and F have associated λ = 2.121 μm H2 emission. One of the two 6 cm continuum sources in the region, VLA 1623E, coincides with CO clump C. The dense ambient gas probed by H13CO+ shows no correlation with the dust continuum peaks in the region, interpreted as evidence of gas-phase depletion onto dust grains. We argue that the H13CO+ peak, which coincides with a water maser, traces the interaction between the outflow and dense gas in the protostellar core. The fractional abundance there is given by X[H13CO+] ≈ 3 × 10-10. The nondetections of H13CN, SO, and SiO allow limits to be placed on their relative abundances at the H13CO+ peak.