  We present a molecular line study of the Sh2-138 (IRAS 22308+5812)
hub-filament system with an aim to investigate its structure and kinematics.
Archival CO molecular line data from the Canadian Galactic Plane Survey
(CO(J=1-0)) for the wider region (50arcminx50arcmin) and the James Clerk
Maxwell Telescope (CO(3-2), 13CO(3-2), and C18O(3-2)) for the central portion
(5arcminx5arcmin) have been utilised. Analysis of the CO(1-0) spectra for the
extended region in conjunction with the hub and filament identification using
column density map and the getsf tool, respectively, reveals a complex
structure with the spectral extraction for the central position displaying
multiple velocity components. Based on the Herschel 70 micron warm dust
emission, one of the filaments in the extended region was inferred to be
associated with active star formation, and is host to a Bolocam 1.1 mm clump of
1606 Msun. Integrated intensity map of 13CO(3-2) emission, constructed from
clumps detected at above 5sigma in position-position-velocity space, reveals
three filamentary structures (labelled W-f, SW-f, and SE-f) in the central
portion. Velocity gradients observed in 13CO(3-2) position-velocity slices
point to longitudinal gas flow along the filaments into the central region.
Filaments W-f, SW-f, and SE-f were calculated to have observed line masses of
32, 33.5, and 50 Msun/pc , respectively. The cloud was found to be dominated by
supersonic and non-thermal motions, with high Mach numbers (>3) and low thermal
to non-thermal pressure ratio (0.01-0.1).
