GMC Collisions As Triggers of Star Formation. IX. Chemical Evolution
Chia-Jung Hsu, Jonathan C. Tan, Jonathan Holdship, Duo, Xu, Serena, Viti, Benjamin Wu, and Brandt Gaches

TL;DR
This study uses 3D magnetohydrodynamics simulations to explore the chemical evolution and astrochemical signatures of giant molecular cloud collisions, revealing how such events influence molecular abundances, physical conditions, and star formation indicators.
Contribution
It provides detailed chemical and physical modeling of colliding versus non-colliding GMCs, highlighting the impact of collisions on molecular abundances and cloud properties, with implications for interpreting IRDC observations.
Findings
Colliding GMCs produce denser, warmer clumps with higher CO depletion.
Low cosmic ray ionization rates best match observed IRDC properties.
Chemical signatures differ significantly between colliding and non-colliding clouds.
Abstract
Collisions between giant molecular clouds (GMCs) have been proposed as a mechanism to trigger massive star and star cluster formation. To investigate the astrochemical signatures of such collisions, we carry out 3D magnetohydrodynamics simulations of colliding and non-colliding clouds exposed to a variety of cosmic ray ionization rates (CRIRs), , following chemical evolution including gas and ice-phase components. At the GMC scale, carbon starts mostly in , but then transitions into C, CO, followed by ice-phase CO and as dense, cooler filaments, clumps and cores form from the clouds. The oxygen budget is dominated by O, CO and water ice. In dense regions, we explore the gas phase CO depletion factor, , that measures the extent of its freeze-out onto dust grains, including dependence on CRIR and observables of mass surface density and temperature. We…
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Taxonomy
TopicsAstrophysics and Star Formation Studies · Atmospheric Ozone and Climate · Atomic and Molecular Physics
