| Description |
One of the early discoveries made with Herschel during the science demonstration phase is the fascinating omnipresence of filamentary structures in the cold interstellar medium and the apparently intimate relationship between the filaments and the formation process of prestellar cloud cores. Our first results from the Gould Belt survey in the Aquila Rift and Polaris Flare regions suggest a picture of core formation according to which filaments form first in the diffuse ISM, probably as a result of interstellar turbulence, and then prestellar cores arise from gravitational fragmentation of the densest filaments. To get further insight into the formation of prestellar cores, it is crucial to clarify the origin and nature of the filaments seen in the wide-field SPIRE-PACS images. Here, we propose follow-up observations of the central parts of two selected filaments with the SPIRE and PACS spectrometers to characterize the physical conditions of the gas and test the hypothesis that the filaments are formed behind low-velocity interstellar shock waves associated with the dissipation of turbulent energy. If this is indeed the case, we expect to detect a number of emission lines such as [CII] (at 158 microns) and [CI] (at 609 microns), and several high-J CO lines which are primary coolants of the postshock gas. |
