The Structure of an 80 Parsec Long Massive Filament

Abstract Using new Institut de Radioastronomie Millimétrique 30 m telescope N 2 H + , C 18 O J = 1–0 and Atacama Pathfinder Experiment telescope 13 CO and C 18 O J = 2–1 maps together with archival far-infrared continuum data, and 12 CO, and 13 CO J = 1–0 data, we present a comprehensive analysis of the massive filament CFG024.00+0.48 (G24) across clump-to-cloud scales. Our results show that G24 is an ∼80 pc giant filament with a total mass of ∼10 5 M ⊙ . In the different tracers the filament width is measured to be about ∼2 times the beam size of the observations, as expected for power-law density distributions, giving beam-deconvolved widths in the range from 0.8 to 2.8 pc. We determine a line-of-sight thickness of ∼2.2 pc demonstrating that G24 is not an edge-on, flattened structure. The virial parameter obtained from line mass ( α line,vir = M line,vir / M line ) from the C 18 O (1–0) data is 0.85, and that obtained from Herschel-based H 2 column density is 0.52, suggesting G24 is globally close to virial equilibrium. The distribution of the 40 dust clumps appears to have a “two-tier” fragmentation pattern. For the clump groups, the separation, with a mean/median of 3.68/3.46 pc, is very close to expected length associated with the maximum fragmentation growth rate of λ max = 3.55 ± 0.32 pc estimated for the dust. However, the longitudinal centroid velocity profiles of C 18 O and N 2 H + show oscillation patterns with wavelengths of 9.8 ± 0.1 pc and 9.9 ± 0.1 pc, respectively. This is ∼2 times larger than the corresponding values of λ max of 4.96 ± 0.63 pc and 4.65 ± 1.34 pc, respectively. This suggests that the velocity structure is not dominated by flows directly associated with the fragmentation seen in the dust emission.