CO observations of the dark clouds Heiles 2, L1333, L1778 and L129

Phillips, J. P. and White, G. J. (1981). CO observations of the dark clouds Heiles 2, L1333, L1778 and L129. Monthly Notices of the Royal Astronomical Society, 194 pp. 15–38.



12C16O and 13C16O J = 1→0 lines of the dark clouds Heiles 2(TMC-1), L1333, L1778, and L129 are presented. A velocity discontinuity in H I maps of Heiles 2 is reflected in a corresponding CO temperature change, and interpreted as a Mach ~3 shock propagating through a single molecular cloud. It is suggested that TMC-1 has recently emerged from the shock, and that evolutionary factors account for the apparently anomalous occurrence of cyanopolynes in this source. L1333 has two distinct velocity components at -2.3 and +3.6 km s-2 extending over ~0.1 square degrees. Both clouds are rotating, although the orientations of the rotational axes differ significantly. The observations are interpreted in terms of dynamically interacting molecular clouds, a single contracting cloud, and in terms of a cloud through which a high Mach number (M~35) shock is propagating.

In contrast, L1778 and L129 exhibit simple spatial structures showing a central core surrounded by a more diffuse envelope. No evidence for rotation or multiple velocity components is evident. Visual extinction maps made with similar spatial resolution to the molectular data show a general correspondence of the molecules and dust.

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