A Theoretical Investigation of Environmental Influences on Molecular Clouds and Star Formation

This study presents a theoretical framework for understanding how environmental parameters such as external pressure, turbulence, and magnetic fields govern the stability, fragmentation, and star formation efficiency (SFE) of molecular clouds. Treating the molecular cloud as a self-gravitating equilibrium system weakly coupled to its surrounding interstellar medium, we derive modified hydrodynamic and virial relations incorporating environmental perturbations. Diagnostic quantities including the Jeans mass, virial parameter, and star formation efficiency per free-fall time are analyzed as functions of density, turbulence, magnetic field strength, and external pressure. The results reveal that external compression significantly lowers the critical fragmentation mass, promoting star formation, whereas turbulence and magnetic fields increase internal support, delaying collapse. Contour and parametric analyses demonstrate that the combined effects of these parameters control the efficiency and timescale of star formation. The theoretical predictions are consistent with observations and numerical simulations, bridging the gap between idealized analytic models and realistic galactic environments.