  IRAS 20319+3958 in Cygnus X South is a rare example of a free-floating
globule (mass ~240 Msun, length ~1.5 pc) with an internal HII region created by
the stellar feedback of embedded intermediate-mass stars, in particular, one
Herbig Be star. Here, we present a Herschel/HIFI CII 158 mu map of the whole
globule and a large set of other FIR lines (mid-to high-J CO lines observed
with Herschel/PACS and SPIRE, the OI 63 mu line and the CO 16-15 line observed
with upGREAT on SOFIA), covering the globule head and partly a position in the
tail. The CII map revealed that the whole globule is probably rotating. Highly
collimated, high-velocity CII emission is detected close to the Herbig Be star.
We performed a PDR analysis using the KOSMA-tau PDR code for one position in
the head and one in the tail. The observed FIR lines in the head can be
reproduced with a two-component model: an extended, non-clumpy outer PDR shell
and a clumpy, dense, and thin inner PDR layer, representing the interface
between the HII region cavity and the external PDR. The modelled internal UV
field of ~2500 Go is similar to what we obtained from the Herschel FIR fluxes,
but lower than what we estimated from the census of the embedded stars.
External illumination from the ~30 pc distant Cyg OB2 cluster, producing an UV
field of ~150-600 G0 as an upper limit, is responsible for most of the CII
emission. For the tail, we modelled the emission with a non-clumpy component,
exposed to a UV-field of around 140 Go.
