Alignment of dense molecular core morphology and velocity gradients with ambient magnetic fields
Journal article, 2023
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 v(LSR) 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 & PROP; R-1.82 & PLUSMN; 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.
ISM: kinematics and dynamics
stars: formation
ISM: evolution
ISM: structure
ISM: clouds
ISM: magnetic fields
Author
A. Pandhi
University of Toronto
R. K. Friesen
University of Toronto
L. Fissel
Queen's University
J. E. Pineda
Max Planck Institute for Extraterrestrial Physics
M. C-Y Chen
Queen's University
J. Di Francesco
University of Victoria
National Research Council Canada
A. Ginsburg
University of Florida
H. Kirk
National Research Council Canada
University of Victoria
P. C. Myers
Harvard-Smithsonian Center for Astrophysics
S. S. R. Offner
The University of Texas at Austin
Anna Punanova
Chalmers, Space, Earth and Environment, Onsala Space Observatory
F. Quan
University of Toronto
E. Redaelli
Max Planck Institute for Extraterrestrial Physics
E. Rosolowsky
University of Alberta
S. Scibelli
University of Arizona
Y. M. Seo
California Institute of Technology (Caltech)
Y. Shirley
University of Arizona
Monthly Notices of the Royal Astronomical Society
0035-8711 (ISSN) 1365-2966 (eISSN)
Vol. 525 1 364-392Subject Categories
Astronomy, Astrophysics and Cosmology
Fusion, Plasma and Space Physics
DOI
10.1093/mnras/stad2283