SEMINAR:- The Role of Magnetic Fields during the Evolution from the DR21 Filament to Massive Dense Cores
The speaker presents Submillimeter Array dust polarization and molecular line observations in the 345 GHz band of six massive dense cores in the DR21 filament. The dust polarization shows complex magnetic field structures in the massive dense cores with sizes of 0.1 pc, in contrast to the ordered magnetic fields of the parsec-scale filament. The analysis of the angular dispersion functions yields a plane-of-sky magnetic field strength of 0.4–1.7 mG for the massive dense cores. The virial parameters of kinematic, magnetic, and gravitational energies show that the gravitational energy in the filament dominates magnetic and kinematic energies, while the kinematic energy dominates in the cores. Comparing the molecular line and dust polarization data, we find that the velocity gradients appear to be randomly oriented relative to the magnetic fields. The linewidth difference between neutral and ionic molecules suggest the existence of ambipolar diffusion with maximum a few mG magnetic field strength in the massive cores. Our work suggests that although magnetic fields may play an important role in a collapsing filament, the kinematics arising from gravitational collapse must become more important than magnetic fields during the evolution from filaments to massive dense cores.
時間：2018.11.20(二) 10:30~11:30
地點：香港中文大學 科學館北座G26室
講者：慶道沖 博士 Dr. Tao-Chung CHING(中國科學院 國家天文台 星際介質組)
語言：英語
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此活動由香港中文大學物理系主辦。
