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EPoS Contribution
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A Unified Explanation of Zeeman Measurements and Polarized Thermal Dust Emission
Hua-bai Li CUHK, Hong Kong, CN | |
| At the beginning of the 21st century, the prevailing belief was that primarily super-Alfvénic turbulence could rival gravity in the process of star formation. However, in the following decade, the perception began to shift as polarized thermal dust emission indicated that cloud-scale magnetic fields were predominantly ordered, suggesting that both turbulence and gravitational contraction were anisotropic. Meanwhile, the relationship between the magnetic field (B) and density (n), B~n2/3, derived from Zeeman measurements, was interpreted as isotropic gravitational collapse. The discrepancy in the interpretations of these two major magnetic field tracers remains a puzzle, as discussed in the latest PPVII review chapter. The logic and data behind the mystery will be discussed, followed by our solution -- I will demonstrate that a MHD simulation calibrated by polarimetry observations (i.e., ordered cloud-scale B-fields) can naturally replicate Zeeman results. | |
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| Caption: Sub-Alfvénic and magnetically trans-critical MHD cloud simulations (Cao & Li 2023) can replicate both Zeeman (e.g., Jiang, Li & Fan 2020) and polarimetry (e.g., Zhang et al. 2019) observations. | |
| Collaborators: Z. Cao, Juelich, DE |
Key publication
Relevant topic(s): Cores Magnetic Fields Turbulence |
| Relevant Big Question: The role of turbulence and magnetic fields in regulating gravitational contraction. | |