ALMA-IRDC: dense gas mass distribution from cloud to core scales
Artikel i vetenskaplig tidskrift, 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


A. T. Barnes

Universität Bonn

J. D. Henshaw


F. Fontani

Max-Planck-Institut für extraterrestrische Physik

Istituto nazionale di astrofisica (INAF)

J. E. Pineda

Max-Planck-Institut für extraterrestrische Physik

Giuliana Cosentino

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik, Extragalaktisk astrofysik

Jonathan Tan

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

University of Virginia

P. Caselli

Max-Planck-Institut für extraterrestrische Physik

I Jimenez-Serra

Centro de Astrobiología (INTA-CSIC)

Chi Yan Law

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik, Extragalaktisk astrofysik

A. Avison

University of Manchester

F. Bigiel

Universität 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

Universität Bonn

R. J. Parker

University of Sheffield

A. Sanchez-Monge

Universität zu Köln

K. Wang

Beijing University of Technology

Monthly Notices of the Royal Astronomical Society

0035-8711 (ISSN) 1365-2966 (eISSN)

Vol. 503 3 4601-4626


Subatomär fysik

Astronomi, astrofysik och kosmologi

Annan fysik



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