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Session 17 - Molecular Clouds and Star Formation.
Oral session, Monday, June 10
NGC 6334 is unique among giant H II/ star formation regions in that it has at least 7 distinct sites of active massive star formation. We have mapped the NGC 6334 star formation region in several transitions of CO and CS with the CSO. The CO lines give the overall morphology of the gas, while the CS lines show where the dense gas lies. We have used an LVG excitation model to determine the physical conditions (column density, volume density, kinetic temperature, and mass) of the gas at each site of star formation.
One of the radio sources, NGC 6334 A, has a shell-like morphology in 6 cm radio continuum (Rodriguez et al. 1982) with faint radio (Rodriguez et al. 1988) and NIR (Harvey et al. 1987) emission extending in bipolar lobes to the north and south of the H II region. We have discovered a rotating disk or toroid of molecular gas, which is probably responsible for the bipolarity of the diffuse radio and NIR emission. In addition to the mm observations, we have also imaged NGC 6334 A in the NH_3 (3,3) line with the VLA. We find several clumps of emission in the region, only two of which are spatially coincident with the H II region. Of the three other NH_3 emission features, one is coincident with the H_2O maser position (Rodriguez et al. 1988) \sim15^'' to the west, and a second is coincident with IRS 20 (Harvey et al. 1987), an unresolved 20 \mum source \sim20^'' southwest of the H II region. The last source of NH_3 emission is not associated with any other line or continuum feature in the region. The two sources west of NGC 6334 A seem to be additional sites of star formation in the region, probably protostars.
Program listing for Monday