Department of Physics, CUHK 香港中文大學物理系

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📣📣📣 Prof. Hua-Bai Li's team discovers self-gravity slows turbulence decay in stellar nurseries 📣📣📣

A breakthrough study led by researchers at The Chinese University of Hong Kong reveals how self-gravity sustains turbulence within dense star-forming clouds. Published in The Astrophysical Journal, the work resolves a decades-old paradox: why molecular cloud turbulence persists despite expectations of rapid decay.

Using high-resolution magnetohydrodynamic (MHD) simulations, Mr. Shibo Yuan and Prof. Hua-bai Li demonstrate that while turbulence decays rapidly in low-density regions (rate: −0.11 km/s/Myr), it remains nearly constant in dense cores (>1,800 H₂/cm³) when self-gravity is present (rate: −0.03 km/s/Myr). This density-dependent decay—absent in non-self-gravitating models—stems from gravitational potential energy released during core formation, countering turbulence dissipation.

Crucially, the sustained turbulence in high-density cores occurs without collapse, challenging prior assumptions. Because, besides collapsing, turbulence-concentrated volumes also release gravitational potential energy. The findings align with recent observations of rising Alfvén Mach numbers in dense regions. Self-gravity secretly fuels turbulence right where stars are born.

Data Availability: CUHK Repository DOI: 10.48668/KDQO4F

Full Paper: https://iopscience.iop.org/article/10.3847/1538-4357/ade5b6

Photo caption: The waterfall plot depicts the decay of turbulence with self-gravity (left panel) and without self-gravity (right panel). Each line perpendicular to the time axis consists of the binned σv-n pairs for a single time snapshot. In the high-density regions, σv exhibits significantly different fluctuations between the two cases; whereas, in low-density regions it decays steadily and similarly.