Research

Links to publications can be found in the “Selected Recent Publications” section below.

News

7. Projection Is All You Need: Interpreting Polarization Measurements in the Orion Clouds with Sub-Alfvénic MHD Simulations

The first detection of the ambipolar diffusion scale originates from NGC 6334 (Tang et al. 2018), located in the sting of the Scorpio constellation; thus, we named the code.

4. Impeding Turbulence Decay in Self-gravitating Cloud Cores

The waterfall plot depicts the decay of cloud turbulence with (left) and without (right) self-gravity.  In the high-density regions, σv exhibits significantly different fluctuations between the two cases; whereas, in low-density regions it decays steadily and similarly.

2. A new probe of the alignments between magnetic fields and protostellar disks.

Education

• PhD, Department of Astronomy and Physics, Northwestern University, 2006

Position

• 2025-now, Professor, Department of Physics, The Chinese University of Hong Kong
• 2019-2025, Associate Professor, Department of Physics, The Chinese University of Hong Kong
• 2013-2019, Assistant Professor, Department of Physics, The Chinese University of Hong Kong
• 2009-2013, Postdoctoral Fellow, Max Planck Institute for Astronomy
• 2006-2009, Postdoctoral Fellow, Harvard-Smithsonian Center for Astrophysics
• 2000-2006, Research/Teaching Assistant, Northwestern University
• 1997-1999, Second Lieutenant, Taiwanese Marine Corp

Research Interests

• Star formation
• Interstellar medium turbulence and magnetic fields
• Astronomical instrumentation

Selected Recent Publications

• “Anchoring Magnetic Field in Turbulent Molecular Clouds“, Li, H.-b., Dowell, C. D., Goodman, A., Hildebrand, R. and Novak, G., ApJ 704, 891 (2009). 
• “The Alignment of Molecular Cloud Magnetic Fields with the Spiral Arms in M33“, Li, H.-b. and Henning, T., Nature 479, 499 (2011). 
• “The Link between Magnetic Fields and Cloud/Star Formation“, Li et al., A Chapter of Protostars and Planets VI, (2014).
• “Anchoring Magnetic Field in Turbulent Molecular Clouds II – from 0.1 to 0.01 Parsec“, Zhang, Y. (Ph.D. student), Guo, Z. (M.Phil. student), Wang H.H. and Li, H.-b., ApJ 871, 98 (2019).
• “A comparison between magnetic field directions inferred from Planck and starlight polarimetry towards Gould Belt Clouds“, Q. Gu & H.-b. Li, ApJL 871, L15 (2019).
• “Magnetic Fields in Molecular Clouds—Observation and Interpretation“, LI, H.-b. Galaxies 2021, 9, 41 (2021).

• “The link between magnetic fields and filamentary clouds: bimodal cloud orientations in the Gould Belt“, Li, H.-b., Fang, M., Henning, T. and Kainulainen, J., MNRAS, doi:10.1093/mnras/stt1849 (2013). 
• “Self-similar Fragmentation Regulated by Magnetic Fields in a Region Forming Massive Stars“, Li, H.-b., Yuen K. H., Otto F., Leung P. K., et al., Nature, (2015). 
• “The link between magnetic field orientations and star formation rates“, H.-b. Li, H.J. Jiang, X.D. Fan, Q.L. Gu and Y.P. Zhang, Nature Astronomy 1, 0158 (2017).
• “The link between magnetic fields and filamentary clouds II: Bimodal linear mass distributions“, Law C. Y. (M.Phil student), Li, H.-B. and Leung, P. K., MNRAS 484, 3604 (2019).
• “Bayesian Revisit of the Relationship between the Total Field Strength and the Volume Density of Interstellar Clouds“, H.J. Jiang, H.-b. Li, X.D. Fan, ApJ 890, 153 (2020).
• “The links between magnetic fields and filamentary clouds III: field regulated mass cumulative functions“, Law C. Y. (M.Phil student), Li H.-B., Cao Z. (Ph.D. student) and Ng C.-Y., MNRAS 498, 850 (2020).
• “Turbulence in Zeeman Measurements from Molecular Clouds“, Zhuo Cao (Ph.D. student) and Hua-bai Li, ApJL, 946, L46 (2023) 

• “Evidence of Dynamically Important Magnetic Fields in Molecular Clouds“, Li, H.-b., Blundell, R., Hedden, A., Kawamura, J., Paine, S. and ong, E., MNRAS 411, 2067 (2011). 
• “Velocity Anisotropy in Self-gravitating Molecular Clouds. I. Simulation“, Otto, F. ( Postdoc), Ji, W. (exchange student) and Li, H.-b., ApJ 836, 95 (2017). 
• “Velocity Anisotropy in Self-gravitating Molecular Clouds. II. Observation“, Luk, S.-S. (M.Phil student), Li, H.-b., and Li, D., ApJ 928, 132 (2022).
• “Impeding Turbulence Decay in Self-gravitating Cloud Cores“, Yuan, S. (Ph.D. student) and Li, H.-b., ApJ, 988, 132 (2025). 

Turbulence Induced Ambipolar Diffusion

• “Probing the Turbulence Dissipation Range and Magnetic Field Strengths in Molecular Clouds“, Li, H.-b. and Houde, M., ApJ 677, 1151 (2008).
• “Tracing Turbulent Ambipolar Diffusion in Molecular Clouds“, Li, H.-b., Houde, M., Lai, S. and Sridharan, T. K., ApJ 718, 905 (2010).
• “Probing the Turbulence Dissipation Range and Magnetic Field Strengths in Molecular Clouds II. Directly Probing the Ion-neutral Decoupling Scale“, Tang, K.S. (M.Phil student), Li, H.-b. and Lee, W-K, ApJ 862, 42 (2018). 
• “Scorpio: a two-fluid code for ambipolar diffusion simulations informed by recent observational constraints“, Cheng, H. L. (Ph.D. student) et al., RASTI, 2025.

Instrumentation

• “Design and Initial Performance of SHARP, a Polarimeter for SHARC-II Camera at the Caltech Submillimeter Observatory“, Li, H.-b., Dowell, D., Kirby, L., Novak, G. and Vaillancourt, J., Applied Optics 47, 422 (2008).
• “Atacama sub-millimeter telescope experiment polarimeter (APol) I: design and lab-test result“, Y. Zhang, H.-B. Li, D. Lühr, T. Takekoshi, T. Oshima and Q. Gu, Applied Optics 59, 2593 (2020).
• “A control system for the ASTEPolarimeter: design and testing“, Lühr Sierra, Melillanca, Vargas and H.-B. Li, Proc. SPIE 11452, Software and Cyberinfrastructure for Astronomy VI, 1145237 (2020).
• “Laser-based frequency-to-pixel mapping method for submillimetre MKID array“, Lyu,  W. (Postdoc), Li,  H.-b., Zhi,  Q., Li,  J., Shi, S., RASTI, Volume 5, rzag007 (2026).

Press Release

• Homegrown cosmic camera to snap the invisible in stardust, CUHK
• CUHK Physicist and Statistician Work Together to Reveal Link Between Magnetic Fields and Birth Rate of Stars, CUHK
• CUHK Physicist Unveils Mystery of Massive Star Formation, CUHK
• As Stars Form, Magnetic Fields Influence Regions Big and Small, Harvard-Smithsonian Center for Astrophysics
• Magnetic fields set the stage for the birth of new stars, Max-Planck-Institut für Astronomie
• Stellar midwives, Max-Planck-Gesellschaft
• Magnetic Fields in Interstellar Clouds, Harvard-Smithsonian Centerfor Astrophysics Weekly Science Update
• Magnetic Fields Play Larger Role in Star Formation than Previously Thought, Harvard-Smithsonian Center for Astrophysics

Research in the Media (Examples):

• 跨校團隊研製「ROGer」相機 盼解恒星誕生之謎, 文匯報
• 中大揭磁場催生「巨星」, 文匯報
• Cosmic magnetic fields act as ‘birth control’ for stars, Hong Kong and US scientists discover, South China Morning Post
• Even though cosmic magnetic fields are much weaker than Earth’s magnetic field, they have an important effect in regulating how stars form, Astronomy Magazine
• Anziehende Geburten im All, Frankfurter Allgemeine
• Magnetic Fields May Rock Cosmic Cradles for Unborn Stars, Space.com
• Magnetic Fields Guide Star Birth, Space.com
• Magnetic Fields Set Stage for Birth of New Stars, Science Daily
• Birth Control for Stars, Science Now