Oral Presentation

Evidence for the gravity-driven and magnetically-regularized gas flows feeding the massive protostellar cluster in Cep A

Author(s): P. Sandhyarani (IISER-T), C. Eswaraiah (IISER-M), Di Li (TU), E. Vázquez-Semadeni (UNAM), G. C. Gómez (UNAM), T. J. Thieme (ASIAA), M. R Samal (PRL), J. W. Wang (EAO), S. P. Lai (NTHU), W. P. Chen (NCU), and D. K. Ojha (TIFR)

Presenter: Eswaraiah Chakali (Indian Institute of Science Education and Research (IISER) Mohali)

The hierarchical interplay among gravity, magnetic fields, and turbulence in forming massive protostellar clusters remains elusive. We present high-resolution (∼14 arcsec ≃ 0.05 pc) 850 μm dust polarization and C$^{18}$O line observations of Cepheus A using JCMT SCUBA-2/POL-2 and HARP. Our analysis reveals aligned gravitational (G), magnetic (B), and velocity fields (K) , with an energy hierarchy of E$_{G}$ > E$_{B}$ > E$_{K}$. Gravity, as the primary driver, induces gas flows and drags in B-field lines. Magnetic tension, as a secondary force, regulates turbulence, enabling ordered flows with an accretion rate of ∼2.1 ± 0.4 × 10$^{-4}$ M$_{sun}$ yr$^{-1}$. This challenges the conventional view of B-fields resisting collapse in the clump/hub scale, instead showing cooperation with gravity. The ∼0.6 pc clump-scale B-field (with mean PA ∼ 45°) aligns coherently with fields at cloud (∼5 pc), core (∼0.05 pc), and disk (∼2000 AU) scales, offering new insights into multiscale star formation dynamics.