Simulation Study of Collisions Between Filamentary Molecular Clouds Threaded by Lateral Magnetic Field and Subsequent Evolution
Speaker: Raiga Kashiwagi
Abstract :
Most Stars are thought to be formed inside filamentary molecular clouds. Recent observations have proposed that star formation may be triggered through collisions between filamentary molecular clouds at nearby star-forming regions(Duarte-Cabral et al. 2010; Nakamura et al. 2014). Furthermore, according to Kumar et al. (2020), all luminous clumps with L > 104L⊙ and L > 105L⊙ at distances within 2 and 5 kpc respectively are located at the intersections (referred to as “hubs”) of filaments and this indicates the formation of massive stars preferentially form at the hubs. Based on the above, filament collisions are considered to be a universal and important phenomenon. Understanding the filament collision process will reveal the initial conditions for collision-induced star formation. Therefore, we have been working on 2D-MHD simulations of filament-filament collisions. In this colloquium, we will report on the condition of radial instability of the merged filament and its evolution. As the initial condition, we prepare two identical infinite long filaments, threaded by lateral magnetic fields. The filaments are in magnetohydrostatic equilibrium(Tomisaka 2014; Kashiwagi & Tomisaka 2021). The two filaments collide head-on along the magnetic field lines with relative velocities ranging from transonic to supersonic. If the total line mass of the initial filaments exceeds the critical line mass of the magnetized filament, the shocked region collapses radially. On the other hand, for collisions where the total line mass is below the critical value, the shocked region evolves into a structure that closely resembles the magnetohydrostatic equilibrium state. In addition, the results for the case where the collision direction is perpendicular to the magnetic field lines are also briefly introduced. Finally, we briefly introduce the preliminary results of the Orthogonal collision which is reproduced by the 3D-MHD simulation.