PROBING THE STRUCTURE OF THE NEAREST MOLECULAR CLOUD MBM-12

at 65 pc, mbm12 is the nearest known molecular cloud. located far from sources of fuv radiation, it provides an ideal laboratory to study translucent interstellar gas. mbm12 has been extensively mapped in (13)co(1>0) and 14 molecular cores have been identified in the complex. deduced molecular hydrogen densities range from 10e+3 to 10e+4 cm3 and excitation temperatures are about 10 k. mbm12 is thus a translucent cloud: densities and temperatures for the cores are typical of dark clouds, while visual extinctions (av is about 2 mag) are typical of diffuse clouds. because of the former property, molecules are able to form in abundance in translucent clouds. however, since av is low, the ambient radiation field plays an important role in their chemistry. mbm12 cores have visual extinctions such that h2 > hi and cii > c > co photochemistry is occuring. for mbm12 most of these species have either already been studied or are currently being investigated. missing from, and vital to, any complete characterization of the physical state of the atomic and molecular interstellar medium of the mbm12 complex is any direct measurement of ionized carbon. iso lws observations of cii will be used in conjunction with existing ci, co, and hi data to study the properties of the 14 atomic/molecular cores in the mbm12 complex. iso measurements of cii emission from mbm12 can provide important constraints on models for photodissociation regions (pdrs) in translucent clouds near weak fuv radiation fields. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]