Work

Estimation of the magnetic field strength from ALMA dust polarization in the protocluster G327.29

Year: 2026

Type: article

Abstract: Magnetic fields and turbulence may play crucial roles in the evolution of molecular clouds and ultimately in the formation of dense cores and stars. Despite being studied in many molecular clouds, the exact role of magnetic fields and turbulence in star formation is still poorly understood. We report the high-resolution plane of sky magnetic field ( B pos ) morphology towards the high-mass star-forming region G327.29, obtained with the 12-metre configuration of the Atacama Large Millimeter/sub-millimeter Array (ALMA) telescope. From our analysis, we obtain a complex B pos morphology in which the magnetic field orientation is uniformly distributed across the entire range from −90 to +90 deg. The observed area is composed of one filament and one dense central clump, both of which harbour multiple dense cores. The total magnetic field strengths ( B tot ) in these regions are 1.7 ± 0.8 and 3.6 ± 1.5 mG at a number density ( n ) of 1.5 ± 0.3 × 10 6 and 2.3 ± 0.7 × 10 6 cm −3 , derived using the Davis–Chandrasekhar–Fermi (DCF) angular dispersion function (ADF) method. The corresponding B tot obtained using the Skalidis–Tassis (ST) method are 0.6 ± 0.3 and 1.1 ± 0.5 mG, approximately three times lower. The virial parameters ( α vir ) in these regions are 2.8 ± 1.9 and 0.5 ± 0.4, suggesting that the regions may be gravitationally bound or unbound after accounting the errors. The ratio of turbulent to magnetic energy (∼0.17–0.34) indicates that the magnetic field is dynamically more important than turbulence. The relative influence of turbulence and magnetic fields on core dynamics appears to depend on how B tot scales with gas density ( ρ ) in the densest regions. In summary, this work, enabled by high-resolution ALMA observations, presents a comprehensive analysis of the relative roles of magnetic fields, turbulence, and gravity in regulating high-mass star formation in G327.29.

Source: Astronomy and Astrophysics

DOI: 10.1051/0004-6361/202660048