[CII] dynamics in the S140 region

We report the observation of [C II] emission in a cut through the S140 region together with single pointing observations of several molecular tracers, including hydrides, in key regions of the photon-dominated region (PDR) and molecular cloud [1]. At a distance of 910 pc, a BOY star ionizes the edge of the molecular cloud L1204, creating S140. In addition, the dense molecular cloud hosts a cluster of embedded massive young stellar objects only 75" from the H ii region [e.g. 2, 3]. We used HIFI on Herschel to observe [CII] in a strip following the direction of the impinging radiation across the ionisation front and through the cluster of embedded YSOs. With [C II], we can trace the ionising radiation and, together with the molecular tracers such as CO isotopologues and HCO+, study the dynamical processes in the region. Combining HIFIs high spectral resolution data with ground based molecular data allows us to study the dynamics and excitation conditions both in the ionization front and the dense molecular star forming region and model their physical conditions [4].