A recent study finished by Dr. MA Yingxiu from the Xinjiang Astronomical Observatory of the Chinese Academy of Sciences and her collaborators, have uncovered clear evidence that two large-scale filamentary structures are colliding and merging, a process that is effectively triggering the formation of massive stars. The paper is being published in The Astrophysical Journal. (DOI: 10.3847/1538-4357/ae12f4).

Filamentary structures are ubiquitous in molecular clouds, and collisions between them are considered to be a key process in reshaping the interstellar medium and promoting star formation. The molecular cloud F-NE, associated with the massive star-forming region AGAL323.444+0.096, is an ideal laboratory for how these interactions drive filament evolution and stellar birth.

Using molecular line data of ¹³CO (2–1) and continuum data from far-infrared to near-infrared, the researchers identified two elongated sub-filaments within F-NE, named F-NE-north and F-NE-south. Each filament stretches approximately 25 parsecs in length, with distinct systemic velocities of about -65.25 km/s and -67.38 km/s, respectively.

A detailed analysis of their spatial and kinematic properties revealed three sub-regions where the two filaments appear to be colliding. Key observational signatures of cloud-cloud collisions were identified, including U-shaped and arc-like structures, spatially complementary features between the colliding and impacted clouds, V-shaped structures in position-velocity diagrams, and connecting "bridge" features.

Furthermore, the interacting regions exhibit significantly enhanced velocity dispersion and increased column density. Notably, these collision zones spatially coincide with massive dense clumps, including AGAL323.444+0.096, and young stellar objects. This strong spatial correlation indicates that the collision and merging of filaments effectively create the necessary conditions for the formation of massive stars or clusters.

This study presents the first systematic observational evidence of colliding and merging filamentary structures in cloud F-NE. It not only advances our understanding of the dynamic evolution of filamentary structures, but also provides important clues for exploring the initial conditions of massive star and star cluster formation.

The research was supported by the National Key R&D Program of China and the National Natural Science Foundation of China.

                                                                                      Distribution of the two elongated filamentary structures (shown in blue and red) in F-NE.