Alignment Parameter: Quantify Dense Core Alignment in Star Formation Regions

ABSTRACT :
Dense cores, precursors to high-mass stars, form inside the dense clumps and spatially exhibit diverse degrees of alignments. The large data from recent observations necessitate an efficient method to quantify core alignment and systematically relate it to clump-scale properties. Thus, we introduce the "alignment parameter" to quantify core alignment, and show that it can effectively distinguish between fragmentation modes. We apply it to 1.3 mm dust continuum data from the ASHES survey, demonstrating this parameter is consistent with visual classification. Nevertheless, we conduct correlations between clump-scale parameters and alignment parameters to assess their relation. Also, numerical simulations are used to check for the relation between the core alignment and structure formation, and clump evolution. Both observations and simulations suggest a weak correlation, implying core alignment might be a dynamic and local feature within clump fragmentation.