The Role of Magnetic Fields in Triggered Star Formation of RCW 120

Abstract We report on the near-infrared polarimetric observations of RCW 120 with 1.4 m IRSF telescope. The starlight polarization background stars reveals for first time magnetic field 120. global is along direction 20°, parallel to Galactic plane. strength plane sky 100 ± 26 μ G. around eastern shell shows evidence compression by H ii region. external pressure (turbulent + pressure) and gas density ambient cloud are minimum where breaks out, which explains observed elongation dynamical age 120, depending strength, ∼1.6 Myr G, older than hydrodynamic estimates. In perpendicular field, contrast western greatly reduced strong field. in general reduces efficiency triggered star formation, comparison Triggered formation via “collect collapse” mechanism could occur Core (CFE) found be higher southern shells infrared dark receiving little influence from region, suggesting increase CFE related triggering ionization feedback.