THE STAR-FORMING CORE OF MONOCEROS R2

The central region of the Monoceros R2 molecular cloud has been studie d using molecular line maps, maps in continuum emission, and an M-band (4.7 mu m) absorption spectrum toward Mon R2 IRS 3. Maps were made in the emission lines CO (3-2) H2CO (5(1,5)-4(1,4)), and HCN (4-3), all with a 14'' beam size. CO (2-1) and (CO)-C-13 (3-2) spectra were obtai ned at a dozen positions. Maps of continuum emission were made at 1300 mu m (25'' resolution), 1100 mu m (20'' resolution), 800 mu m (14'' r esolution), and 450 mu m (14'' resolution). The M-band spectrum of IRS 3 has a velocity resolution of 5.2 km s(-1) and shows fundamental vib rational band absorption lines of CO and (CO)-C-13 over a range of rot ational states. The CO map has numerous intensity peaks which, if inte rpreted as clumps, have masses from 0.1 to 3 M.. The large velocity di spersion of these structures implies that they cannot be gravitational ly bound. The brightest GO-emitting gas shows no bipolar distribution with velocity. Diffuse GO-emitting gas with low velocities does have a generally bipolar distribution, but there are no collimated lobes poi nting to a particular source. We conclude that the source (or sources) of the very extended Mon R2 outflow is (are) now inactive. The highes t velocity gas is found toward the embedded young stellar object IRS 3 , suggesting that IRS 3 is the source of a compact outflow, unresolved at our 14'' resolution. The presence of blueshifted CO in the absorpt ion spectrum supports the interpretation of IRS 3 as an outflow source . The H2CO and HCN maps demonstrate that much of the dense gas is dist ributed within three structures having different velocities. The funda mental band absorption lines of (CO)-C-13 show two gas temperatures in the line of sight to IRS 3. The colder (45 K) is identified as gas in the clump surrounding IRS 3, which is seen in emission lines of CO, H 2CO, and HCN. The warmer (310 K) we interpret as gas very close to IRS 3. From the submillimeter continuum maps we identify 11 clumps whose masses lie in the range 3-10 M.. A clump that is prominent in the cont inuum maps but not in the molecular line maps is attributed to heated dust inside the compact H 11 region, where molecules have been destroy ed.