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M. Choi (ASIAA, R.O.C.), N. J. Evans II (University of Texas at Austin), M. Tafalla, R. Bachiller (Observatorio Astronomico Nacional, Spain)
We present the result of molecular line observations of Mon R2. The Mon R2 dense core region was observed with molecular emission lines of CS 5-4, CS 7-6, H2CO 303-202, H2CO 322-221, H2CO 505-404, and HCN 4-3. Maps in lines tracing high density show an arc-like structure surrounding the H II region. Maps of temperature deduced from H2CO line ratios reveal a hot spot with TK > 100 K coincident with a submillimeter continuum peak. Maps of density deduced from CS line ratios indicate that the density peaks near IRS 1 and declines away from it. The spherically averaged data can be modeled equally well with a power-law density profile with an exponent of 0.8-0.9 or a Gaussian density profile with an FWHM of 1.0 pc. In either case, densities in the central region are around 106 cm-3. The derived density gradient suggests that the thermal pressure is not the only source of cloud support, and the relation between the density gradient and the cloud mass suggested from similar studies of other regions also holds in the Mon R2 cloud core.