ALMA-IRDC: dense gas mass distribution from cloud to core scales
Journal article, 2021
Infrared dark clouds (IRDCs) are potential hosts of the elusive early phases of high mass star formation (HMSF). Here, we conduct an in-depth analysis of the fragmentation properties of a sample of 10 IRDCs, which have been highlighted as some of the best candidates to study HMSF within the Milky Way. To do so, we have obtained a set of large mosaics covering these IRDCs with Atacama Large Millimeter/submillimeter Array (ALMA) at Band 3 (or 3 mm). These observations have a high angular resolution (similar to 3 arcsec; similar to 0.05 pc), and high continuum and spectral line sensitivity (similar to 0.15 mJy beam(-1) and similar to 0.2 K per 0.1 km s(-1) channel at the N2H+ (1 - 0) transition). From the dust continuum emission, we identify 96 cores ranging from low to high mass (M = 3.4-50.9M(circle dot)) that are gravitationally bound (alpha(vir) = 0.3-1.3) and which would require magnetic field strengths of B = 0.3-1.0 mG to be in virial equilibrium. We combine these results with a homogenized catalogue of literature cores to recover the hierarchical structure within these clouds over four orders of magnitude in spatial scale (0.01-10 pc). Using supplementary observations at an even higher angular resolution, we find that the smallest fragments (<0.02 pc) within this hierarchy do not currently have the mass and/or the density required to form high-mass stars. None the less, the new ALMA observations presented in this paper have facilitated the identification of 19 (6 quiescent and 13 star-forming) cores that retain >16M(circle dot) without further fragmentation. These high-mass cores contain trans-sonic non-thermal motions, are kinematically sub-virial, and require moderate magnetic field strengths for support against collapse. The identification of these potential sites of HMSF represents a key step in allowing us to test the predictions from high-mass star and cluster formation theories.
stars: massive
ISM: clouds
stars: formation
Author
A. T. Barnes
University of Bonn
J. D. Henshaw
Max Planck Society
F. Fontani
Max Planck Institute for Extraterrestrial Physics
Istituto nazionale di astrofisica (INAF)
J. E. Pineda
Max Planck Institute for Extraterrestrial Physics
Giuliana Cosentino
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Jonathan Tan
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
University of Virginia
P. Caselli
Max Planck Institute for Extraterrestrial Physics
I Jimenez-Serra
Spanish Astrobiology Center (INTA-CSIC)
Chi Yan Law
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
A. Avison
University of Manchester
F. Bigiel
University of Bonn
S. Feng
Chinese Academy of Sciences
National Institutes of Natural Sciences
Academia Sinica
S. Kong
University of Arizona
S. N. Longmore
Liverpool John Moores University
L. Moser
University of Bonn
R. J. Parker
University of Sheffield
A. Sanchez-Monge
University of Cologne
K. Wang
Beijing University of Technology
Monthly Notices of the Royal Astronomical Society
0035-8711 (ISSN) 1365-2966 (eISSN)
Vol. 503 3 4601-4626Subject Categories
Subatomic Physics
Astronomy, Astrophysics and Cosmology
Other Physics Topics
DOI
10.1093/mnras/stab803