PHASE TRANSITIONS IN TRANSLUCENT CLOUDS

we propose to observe the c+ 158micron line emission in order to trace the phase transitions of c in the translucent cloud g236+39 (spring launch) or the edges of the dark cloud l183 (autumn launch). g236+39 has been shown to contain the phase transitions from h/h2 and c+/co, and we will propose to observe the ci 609micron line for comparison to the iso observations. l183 has already be observed in ci line. both g236+39 and l183 have been observed in co and its 13co isotopomer. the c+ observations will be combined with ci observations in order to distinguish the c+/ci and ci/co transitions, which must lie between the cloud edge and the co cores. these phase transitions are a key both to the cloud thermodynamics (governed by the cooling through the c+ line) and the cloud chemistry of cbearing species (governed by the abundance of c+). truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]