THE ROTATING MOLECULAR CORE IN G10.6-0.4 - SYNTHESIS MAPS IN (CO)-C-12-O-18

Using the Owens Valley Radio Observatory millimeter-wave interferomete r, the compact molecular cloud core surrounding the H II region G10.60 -0.4 has been resolved in the (CO)-O-18 J = 1-0 transition. Since this line is most likely optically thin, it is an excellent tracer of the total column density. We find a centrally condensed and flattened (12' '6 x 4''2; 0.3 pc x 0.1 pc) core, which is rotating rapidly with a sub stantial velocity gradient (17 +/- 2 km s-1 pc-1) along the major axis . The core is quite bright (> 10 K), dense (> 10(6) cm-3), massive (10 (3) M.), and embedded in a more extended (>60'') envelope. There is no evidence for absorption, implying that the (CO)-O-18 emitting gas is both optically thin and substantially hotter than the equivalent conti nuum temperature at 3 mm. The systemic velocity of the rotating core i s - 2.5 +/-0.5 km s-1, the same as the systemic velocity of the extend ed cloud.