A researcher at the Xinjiang Astronomical Observatory (XAO) of the Chinese Academy of Sciences conducted a study of the star-forming region Sh2-252 A-B and revealed an active hub-filament system (HFS) driven by global hierarchical collapse rather than cloud-cloud collision.

International PhD student Serikbek Sailanbek from the Star Formation and Evolution Group XAO led the study. The results were published in the Research in Astronomy and Astrophysics.

The data was obtained with the Nanshan 26-m radio telescope and many other data such as CO from PMO 14m telescope. Using multi-tracer molecular line observations (CO isotopologues, NH₃) and far-infrared dust continuum data, the researcher examined high-resolution morphological, kinematic, thermal and dynamical properties of S252A-B.

Six distinct filament branches—F-NE (northeast), F-NW (northwest), F-W (west), F-N (north), F-SW (southwest), and F-SE (southeast)—converge onto the main S252A-B hub and secondary S252A hub in a spoke-like structure, showing hierarchical density from diffuse CO envelope to dense NH₃ cores.

The filaments are coherent in space and velocity, remain cold at around Tₖᵢₙ≈15-18 K with a "shielded flow" that sustains accretion, and the virial parameter (αᵥᵢᵣ~0.4-0.6) confirms that the central hub is gravitationally bound and collapsing.

Double-peaked spectra are detected only toward the south-western edge of the region with no associated young stellar objects, which rules out cloud-cloud collision as the main trigger of star formation in S252A-B.

This work provides definitive evidence for an active hub-filament system and shows that feedback-driven compression and gravitational focusing work together to channel mass toward active star-forming sites.

The study also emphasizes the critical importance of high-resolution kinematic observations for distinguishing between different star formation mechanisms, while delivering key insights into interstellar gas dynamics, turbulence, and the physical processes that drive stellar birth.