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Observations of CO Formula emission from molecular clouds

1981; Oxford University Press; Volume: 197; Issue: 3 Linguagem: Inglês

10.1093/mnras/197.3.745

1365-2966

G. J. White, J. P. Phillips, G. D. Watt,

Atmospheric Ozone and Climate

Extensive observations in the |$J=3\rightarrow2$| transition of carbon monoxide at 345 GHz (870 µm) have been obtained using an indium antimonide heterodyne spectral-line receiver with the United Kingdom 3.8-m Infrared Telescope (UKIRT) at Mauna Kea. Mapping observations of up to ½ deg2 areas are reported towards the sources NGC 1333, 2023, 2024 and 2068. These maps, obtained with a 55-arcsec beam, reveal a number of new molecular hotspots as well as confirming our previous detection of molecular cool-spots. High-quality spectra have been obtained towards the self-absorbed sources NGC 1333 IRS-1, NGC 2071, Mon R2, AFGL 961 and DR 21. These spectra are similar to those observed in lower CO transitions, but there is a tendency for the redshifted wing to be enhanced in the |$J=3\rightarrow2$| transition. Spectral observations are also reported for L1551/HH-29. Analysis of the variation of gas kinetic temperature around several of the mapped sources shows close agreement with the expected grain kinetic temperature, assuming these sources to be irradiated by single central stars of a spectral class similar to that estimated from other methods. The present data support our previous model (from CO |$J=1\rightarrow0$| data) for NGC 2071 and show it to be a rotating cloud.