Radiation-magnetohydrodynamic simulations of HII regions and their associated PDRs in turbulent molecular clouds

摘要: We present the results of radiation-magnetohydrodynamic simulations expansion HII regions and surrounding photodissociation in turbulent, magnetised, molecular clouds on scales up to 4 parsecs, including effects ionising non-ionising ultraviolet radiation x rays from young star clusters. find that region reduces disordered component B field, imposing a large-scale order field around its border. The neutral gas lies along ionisation front, while ionised tends be perpendicular this. highest pressure compressed neutral/molecular is driven towards approximate equipartition between thermal/magnetic/turbulent energy densities, whereas lower divides into quiescent, magnetically dominated regions, and, other hand, demagnetised regions. shows thermal/turbulent equipartition, but with magnetic densities 1 3 orders magnitude lower. A high velocity dispersion (approx 8 km/s) maintained throughout our simulations, despite mean being significantly does not brake length timescales accessible it tend suppress small-scale fragmentation radiation-driven implosion forms globules pillars at edge region. However, relative luminosity has much larger influence than presence or absence field. When relatively soft (as case mass cluster, earliest spectral type B0.5), then less vigorous thick, smooth PDR forms. Movies available this http URL