2023/09/28 by N. K. Bhadari, L. K. Dewangan, Bhadari, N. K. +11 · 1 citation
Chemical Engineering · Engineering · Physics and Astronomy · #Advanced Combustion Engine Technologies #Astrophysics and Star Formation Studies #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Space Exploration and Technology
paper · pdf · doi:10.48550/arxiv.2309.16472
openalex publication_date 2023/09/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present an analysis of the dense gas structures in the immediate surroundings of the massive young stellar object (MYSO) W42-MME, using the high-resolution (0''.31×0''.25) ALMA dust continuum and molecular line data. We performed a dendrogram analysis of H13CO+ (4-3) line data to study multi-scale structures and their spatio-kinematic properties, and analyzed the fragmentation and dynamics of dense structures down to ∼2000 AU scale. Our results reveal 19 dense gas structures, out of which 12 are leaves and 7 are branches in dendrogram terminology. These structures exhibit transonic-supersonic gas motions (1<M<5) with overvirial states (α\rm vir≥2). The non-thermal velocity dispersion-size relation (σ\rm nt-L) of dendrogram structures shows a weak negative correlation, while the velocity dispersion across the sky (δ\mathitV\rm lsr) correlates positively with structure size (L). Velocity structure function (S2(l)1/2) analysis of H13CO+ data reveals strong power-law dependencies with lag (l) up to a scale length of \lesssim 6000 AU. The mass-size (M-R) relation of dendrogram structures shows a positive correlation with power-law index of 1.73±0.23, and the leaf L17 hosting W42-MME meets the mass-size conditions for massive star formation. Blue asymmetry is observed in the H12CO+ (4-3) line profiles of most of the leaves, indicating infall. Overall, our results observationally support the hierarchical and chaotic collapse scenario in the proximity of the MYSO W42-MME.