Alignment of dense molecular core morphology and velocity gradients with ambient magnetic fields

A. Pandhi, R. K. Friesen, L. Fissel, J. E.J. Pineda, P. Caselli, M. C.Y. Chen, J. Di Francesco, A. Ginsburg, H. Kirk, P. C. Myers, S. S.R. Offner, A. Punanova, F. Quan, E. Redaelli, E. Rosolowsky, S. Scibelli, Y. M. Seo, Y. Shirley

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Studies of dense core morphologies and their orientations with respect to gas flows and the local magnetic field have been limited to only a small sample of cores with spectroscopic data. Leveraging the Green Bank Ammonia Survey alongside existing sub-millimeter continuum observations and Planck dust polarization, we produce a cross-matched catalogue of 399 dense cores with estimates of core morphology, size, mass, specific angular momentum, and magnetic field orientation. Of the 399 cores, 329 exhibit 2D vLSR maps that are well fit with a linear gradient, consistent with rotation projected on the sky. We find a best-fit specific angular momentum and core size relationship of J/M ∝ R1.82 ± 0.10, suggesting that core velocity gradients originate from a combination of solid body rotation and turbulent motions. Most cores have no preferred orientation between the axis of core elongation, velocity gradient direction, and the ambient magnetic field orientation, favouring a triaxial and weakly magnetized origin. We find, however, strong evidence for a preferred anti-alignment between the core elongation axis and magnetic field for protostellar cores, revealing a change in orientation from starless and prestellar populations that may result from gravitational contraction in a magnetically-regulated (but not dominant) environment. We also find marginal evidence for anti-alignment between the core velocity gradient and magnetic field orientation in the L1228 and L1251 regions of Cepheus, suggesting a preferred orientation with respect to magnetic fields may be more prevalent in regions with locally ordered fields.

Original languageEnglish (US)
Pages (from-to)364-392
Number of pages29
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - Oct 1 2023


  • ISM: clouds
  • ISM: evolution
  • ISM: kinematics and dynamics
  • ISM: magnetic fields
  • ISM: structure
  • stars: formation

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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