Magnetic fields at the onset of high-mass star formation
Journal article, 2018

Context. The importance of magnetic fields at the onset of star formation related to the early fragmentation and collapse processes is largely unexplored today. Aims. We want to understand the magnetic field properties at the earliest evolutionary stages of high-mass star formation. Methods. The Atacama Large Millimeter Array is used at 1.3 mm wavelength in full polarization mode to study the polarized emission, and, using this, the magnetic field morphologies and strengths of the high-mass starless region IRDC 18310-4. Results. Polarized emission is clearly detected in four sub-cores of the region; in general it shows a smooth distribution, also along elongated cores. Estimating the magnetic field strength via the Davis-Chandrasekhar-Fermi method and following a structure function analysis, we find comparably large magnetic field strengths between ~0.3-5.3 mG. Comparing the data to spectral line observations, the turbulent-to-magnetic energy ratio is low, indicating that turbulence does not significantly contribute to the stability of the gas clump. A mass-to-flux ratio around the critical value 1.0 - depending on column density - indicates that the region starts to collapse, which is consistent with the previous spectral line analysis of the region. Conclusions. While this high-mass region is collapsing and thus at the verge of star formation, the high magnetic field values and the smooth spatial structure indicate that the magnetic field is important for the fragmentation and collapse process. This single case study can only be the starting point for larger sample studies of magnetic fields at the onset of star formation.


Magnetic fields

ISM: clouds

Instrumentation: interferometers

Stars: formation

Stars: individual: IRDC18310


H. Beuther

Max Planck Society

J. D. Soler

Max Planck Society

Wouter Vlemmings

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

H. Linz

Max Planck Society

T. Henning

Max Planck Society

Rolf Kuiper

University of Tübingen

R. Rao

Academia Sinica

R. Smith

University of Manchester

T. Sakai

University of Electro-Communications

K. Johnston

University of Leeds

A. Walsh

Curtin University

S. Feng

Max Planck Society

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 614 A64

Magnetic fields and the outflows during the formation and evolution of stars (OUTFLOWMAGN)

European Commission (EC) (EC/FP7/614264), 2014-05-01 -- 2019-04-30.

Subject Categories

Astronomy, Astrophysics and Cosmology

Fusion, Plasma and Space Physics

Condensed Matter Physics



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7/2/2018 1