FAR-INFRARED ISOPHOT OBSERVATIONS AND THE ENERGY-BALANCE OF A QUIESCENT GLOBULE

We have observed a quiescent small globule, the Thumbprint Nebula, wit h the ISOPHOT far-infrared camera at 100 and 200 mu m. The observed em ission is optically thin thermal emission from dust at a temperature o f similar to 14-16 K. The energy budget of the cloud is studied by con sidering the energy input (interstellar radiation field, ISRF), and ou tputs (scattered and emitted radiation). It is found that the ISRF is sufficient to be the only heating source of dust in the cloud. We have derived values of absorption cross sections of dust at 100 and 200 mu m, and found them to be in good agreement with current dust models.