We present an analysis of multi-wavelength observations of an area of 0 • .27 × 0 • .27 around the Galactic H ii region G18.88−0.49, which is powered by an O-type star (age ∼10 5 years). The Herschel column density map reveals a shell-like feature of extension ∼12 pc × 7 pc and mass ∼2.9 ×10 4 M around the H ii region; its existence is further confirmed by the distribution of molecular ( 12 CO, 13 CO, C 18 O, and NH 3 ) gas at [60, 70] km s −1 . Four subregions are studied toward this shell-like feature, and show a mass range of ∼0.8-10.5 ×10 3 M . These subregions associated with dense gas are dominated by non-thermal pressure and supersonic non-thermal motions. The shell-like feature is associated with the H ii region, Class I protostars, and a massive protostar candidate, illustrating the ongoing early phases of star formation (including massive stars). The massive protostar is found toward the position of the 6.7 GHz methanol maser, and is associated with outflow activity. Five parsec-scale filaments are identified in the column density and molecular maps, and appear to be radially directed to the dense parts of the shell-like feature. This configuration is referred to as a "hub-filament" system. Significant velocity gradients (0.8-1.8 km s −1 pc −1 ) are observed along each filament, suggesting that the molecular gas flows towards the central hub along the filaments. Overall, our observational findings favor a global non-isotropic collapse scenario as discussed in Motte et al. (2018), which can explain the observed morphology and star formation in and around G18.88−0.49.

We present an analysis of multiwavelength observations of Monoceros R1 (Mon R1) complex (at d ∼760 pc). An elongated filament (length ∼14 pc, mass ∼1465 M ⊙) is investigated in the complex, which is the most prominent structure in the Herschel column density map. An analysis of the FUGIN 12CO(1–0) and 13CO(1–0) line data confirms the existence of the filament traced in a velocity range of [−5, +1] km s−1. The filament is found to host two previously known sites IC 446 and IC 447 at its opposite ends. A massive young stellar object (YSO) is embedded in IC 446, while IC 447 contains several massive B-type stars. The Herschel temperature map reveals the extended warm dust emission (at T d ∼ 15–21 K) toward both the ends of the filament. The Spitzer ratio map of 4.5 μm/3.6 μm emission suggests the presence of photodissociation regions and signature of outflow activity toward IC 446 and IC 447. Based on the photometric analysis of point-like sources, clusters of YSOs are traced mainly toward the filament ends. The filament is found to be thermally supercritical showing its tendency of fragmentation, which is further confirmed by the detection of a periodic oscillatory pattern (having a period of ∼3–4 pc) in the velocity profile of 13CO. Our outcomes suggest that the fragments distributed toward the filament ends have rapidly collapsed, and had formed the known star-forming sites. Overall, the elongated filament in Mon R1 is a promising sample of the “end-dominated collapse” scenario, as discussed by Pon et al. (2011, 2012).

We study multiwavelength and multiscale data to investigate the kinematics of molecular gas associated with the star-forming complexes G045.49+00.04 (G45E) and G045.14+00.14 (G45W) in the Aquila constellation. An analysis of the FUGIN 13CO(1–0) line data unveils the presence of a giant molecular filament (GMF G45.3+0.1; length ∼75 pc, mass ∼1.1 × 106 M ⊙) having a coherent velocity structure at [53, 63] km s−1. The GMF G45.3+0.1 hosts G45E and G45W complexes at its opposite ends. We find large-scale velocity oscillations along GMF G45.3+0.1, which also reveals the linear velocity gradients of −0.064 and +0.032 km s−1 pc−1 at its edges. The photometric analysis of point-like sources shows the clustering of young stellar object (YSO) candidate sources at the filament’s edges where the presence of dense gas and H ii regions are also spatially observed. The Herschel continuum maps along with the CHIMPS 13CO(3–2) line data unravel the presence of parsec scale hub-filament systems (HFSs) in both sites, G45E and G45W. Our study suggests that the global collapse of GMF G45.3+0.1 is end dominated, with the addition to the signature of global nonisotropic collapse at the edges. Overall, GMF G45.3+0.1 is the first observational sample of filament where the edge-collapse and the hub-filament configurations are simultaneously investigated. These observations open the new possibility of massive star formation, including the formation of HFSs.