Date & Time: 2026/April/9 17:00-18:00, Venue: Zoom TV Conference System. This is an informal seminar on the formation of stars and planets. We welcome anyone interested in the subject.
Abstract:
Recent observations have identified hub-filament systems (HFSs) as major formation sites of massive stars and star clusters. Some HFSs show multiple filaments aligned radially toward a central dense hub, but the physical origin of these structures remains unclear. We propose a new formation mechanism in which a fast magnetohydrodynamic shock interacts with a molecular cloud characterized by an hourglass-shaped magnetic field and density inhomogeneity. Three-dimensional magnetohydrodynamic simulations show that this interaction forms radially aligned filaments with lengths of 1–3 pc and widths of 0.06–0.08 pc. High-density filamentary gas selectively exhibits inward velocities of 1–4 km s-1 that increase toward the hub center, while the ambient low-density inter-filament gas retains low velocities regardless of radius. Mass accretion onto the hub is channeled through dense filaments. The filament formation is driven by oblique shocks generated at the bent magnetic field lines. The resulting post-shock amplification of the tangential magnetic field induces a magnetically guided inflow. The shock-interface interaction amplifies density perturbations, resembling Richtmyer-Meshkov instability modes, which promotes the fragmentation of the shocked layer into multiple filaments. This process can explain both the morphology of radially aligned filaments and the selective mass accretion observed in HFSs.
他、会議報告、速報など、飛び入りも歓迎します。今回もしくは次回以降、話題提供できる方は世話人までメールしていただけましたら幸いです。
Participants:, Affiliations:
次回：TBD
連絡世話人：冨永遼佑（東京科学大学） tominaga.r.aa[at]m.titech.ac.jp