Magnetic Fields in Molecular Clouds—Observation and Interpretation

The Zeeman effect and dust grain alignment are two major methods for probing magnetic fields (B-fields) in molecular clouds, largely motivated by the study of star formation, as the B-field may regulate gravitational contraction and channel turbulence velocity. I will review our observations of B-fields over the past decade, along with our interpretation. Galactic B-fields anchor molecular clouds down to cloud cores with scales around 0.1 pc and densities of 104–5 H2/cc. Within the cores, turbulence can be slightly super-Alfvénic, while the bulk volumes of parental clouds are sub-Alfvénic. The consequences of these largely ordered cloud B-fields on fragmentation and star formation are observed. The above paradigm is very different from the generally accepted theory during the first decade of the century, when cloud turbulence was assumed to be highly super-Alfvénic. Thus, turbulence anisotropy and turbulence-induced ambipolar diffusion are also revisited.

Huabai Li (The Chinese University of Hong Kong)
Remote Talk Meeting ID: 622 393 7478 Passcode: 2BYguM
Ke Wang
Thursday, May 6, 2021 - 4:00PM to Thursday, May 6, 2021 - 5:00PM
I received the Ph.D. degree in astrophysics from Northwestern University in 2006. Afterwards, I had worked in the Harvard-Smithsonian Center for Astrophysics and Max Planck Institute for Astronomy. In Aug. 2013, I started the current position in the Department of Physics, The Chinese University of Hong Kong. My research group study how magnetic fields and turbulence regulate star formation; wee use various novel methods in observations, numerical simulations and instrumentation.