摘要
Science Advances, 12(17), eady2189 (2026) The hierarchical interplay among gravity, magnetic fields, and turbulence in forming massive protostellar clusters remains elusive. We present high-resolution ( $\sim$ 14 arcsec$\simeq$0.05 pc) 850$μ$ m 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$E_{\mathrm{G}}$>$E_{\mathrm{B}}$>$E_{\mathrm{K}}$ . 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$\sim$2.1$\pm$0.4$\times$10 $^{-4}$M $_\odot$yr $^{-1}$ . This challenges the conventional view of B-fields resisting collapse in the clump/hub scale, instead showing cooperation with gravity. The$\sim$ 0.6 pc clump-scale B-field (with mean PA$\sim$45°) aligns coherently with fields at cloud ( $\sim$ 5 pc), core ( $\sim$ 0.05 pc), and disk ( $\sim$ 2000 AU) scales, offering new insights into the role of magnetic fields in multiscale star formation dynamics.