2023MNRAS.519.3851P

With the Atacama Pathfinder Experiment mapping observations of ¹³CO and C¹⁸O (2-1) complemented with Herschel data, we have carried out a comprehensive analysis on dynamics of the G345.51+0.84 (G345 hereafter) region. It is composed of two physically connected components: the blue-shifted (i.e. G345Blue), and red-shifted velocity (i.e. G345Red) clouds, which peak near -12.5 km s^–1 and -10.5 km s^–1, respectively. The former cloud contains one compact clump (C1), whereas the latter constitutes one filament (Fil345) and four clumps (C2-C5) inside it. The filament is ∼2.6 pc-long and ∼0.52 pc-wide with a median line-mass of M_line = 183 ± 98 M_⊙ pc^–1, being overall in equilibrium but locally gravitationally bound especially around the clumps. The presence of high-mass protostars in the C2 clump and higher M_line values around it collectively indicates that Fil345 is an ongoing high-mass star-forming filament. The detailed dynamics analysis reveals the cloud-cloud collision scenario between G345Blue and G345Red in the global region studied here, and the longitudinal and radial velocity gradients in the filament indicative of directed mass accretion along the two orthogonal directions. Further analysing the possible mechanism of filament formation for Fil345, we suggest that it presently grows in mass by a hybrid of mass accretion and cloud-cloud collision.