2025A&A...698A.119S

Context. Filaments are common features in molecular clouds and they play a key role in star formation. Studying their life cycle is essential to fully understand the star formation process.
Aims. Using high-resolution magnetohydrodynamical simulations including early stellar feedback (jets and H II regions), we aim to characterise the impact of magnetic field (B) and stellar feedback on the evolution of filamentary structures in star-forming clouds.
Methods. We performed two numerical simulations of a collapsing 10⁴ M_⊙ cloud with different mass-to-flux ratios (μ = 2 and μ = 8). Using DisPerSE, we extracted the three-dimensional filamentary network and analysed its morphological and physical properties as it evolves throughout the star formation event.
Results. We find that the B plays a central role in shaping the density structures as the clouds evolve. With a weak field, the cloud develops a single central hub, while in strong B fields the cloud maintains a sparser filamentary network. A stronger magnetisation also delays star formation, although the two runs ultimately achieved similar star formation efficiencies. We observed that the filaments in the simulations follow two distinct evolutionary pathways. In the strongly magnetised case, filaments are predominantly perpendicular to B lines, favouring a parallel alignment in the weak field cloud. Furthermore, while always accreting, filaments exhibit faster flows towards the hub relative to the surrounding gas. In the weakly magnetised run, the central hub dominates the dynamics, and filaments exhibit faster flows as they approach the central hub. Finally, once the expanding H II region impacts the filaments, they align to B independently of the initial configuration.
Conclusions. Magnetic fields play a critical role in shaping the structure and dynamics of molecular clouds. Stronger magnetic fields slow the cloud's evolution and inhibit the formation of central hubs, promoting a broader filamentary network instead. However, ionising feedback dominates the late-stage evolution, overriding the initial differences and dictating the final filament configuration.