The ratio of N(C$\mathsf{^{18}}$O) and A$\mathsf{_{V}}$ in Chamaeleon I and III-B - Using 2MASS and SEST

摘要: We investigate the relationship between C 18 O column density and visual extinction in Chamaeleon I a part of III molecular cloud. The densities, N(C O), are calculated from J = 1-0 rotational line data observed with SEST telescope. extinctions, A v , derived using JHK photometry 2MASS survey NICER color excess technique. In contrast previous results Hayakawa et al. (2001, PASJ, 53, 1109), we find that average O)/A ratios similar Cha III, lie close to values for other clouds, i.e. O) 2 x 10 14 cm -2 (A - 2). find, however, clear deviations this towards individual clumps. Larger than can be found clumps associated active star forming region northern I. On hand, some regions relatively quiescent southern show smaller also very shallow proportionality . suggests is heavily depleted these regions. As degree depletion proportional gas density, probably contain dense, cold cores, which do not stand out CO mappings. comparison dust temperature map ISO shows most prominent potentially cores indeed coincides minimum. It seems therefore feasible use Av together identifying cold, dense large scale