Volume 600, April 2017
|Number of page(s)||9|
|Published online||04 April 2017|
ALMA survey of massive cluster progenitors from ATLASGAL
Limited fragmentation at the early evolutionary stage of massive clumps⋆
1 Max Planck Institute for Radioastronomy, Auf dem Hügel 69, 53121 Bonn, Germany
2 OASU/LAB-UMR5804, CNRS, Université Bordeaux, allée Geoffroy Saint-Hilaire, 33615 Pessac, France
3 Institut de Planétologie et d’Astrophysique de Grenoble, Univ. Grenoble Alpes – CNRS-INSU, BP 53, 38041 Grenoble Cedex 9, France
4 Laboratoire AIM Paris Saclay, CEA-INSU/CNRS-Université Paris Diderot, IRFU/SAp CEA-Saclay, 91191 Gif-sur-Yvette, France
5 Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
6 Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
7 Univ. Lyon, ENS de Lyon, Univ Lyon1, CNRS, Centre de Recherche Astrophysique de Lyon UMR5574, F-69007, Lyon, France
8 IRAM, 300 rue de la piscine, 38406 Saint-Martin-d’ Hères, France
9 School of Physics and Astronomy, University of Exeter, UK
10 Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester, M13 9PL, UK
11 Astrophysics Research Institute, Liverpool John Moores University, UK
12 Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Mexico
13 School of Physics & Astronomy, Cardiff University, UK
14 Departments of Astronomy and Physics, University of Florida, USA
15 European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany
16 INAF–Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
17 IAPS–INAF, Via Fosso del Cavaliere, 100, 00133 Rome, Italy
18 School of Physical Sciences, University of Kent, Ingram Building, Canterbury, Kent CT2 7NH, UK
Received: 20 September 2016
Accepted: 1 March 2017
The early evolution of massive cluster progenitors is poorly understood. We investigate the fragmentation properties from 0.3 pc to 0.06 pc scales of a homogenous sample of infrared-quiet massive clumps within 4.5 kpc selected from the ATLASGAL survey. Using the ALMA 7 m array we detect compact dust continuum emission towards all targets and find that fragmentation, at these scales, is limited. The mass distribution of the fragments uncovers a large fraction of cores above 40 M⊙, corresponding to massive dense cores (MDCs) with masses up to ~400 M⊙. Seventy-seven percent of the clumps contain at most 3 MDCs per clump, and we also reveal single clumps/MDCs. The most massive cores are formed within the more massive clumps and a high concentration of mass on small scales reveals a high core formation efficiency. The mass of MDCs highly exceeds the local thermal Jeans mass, and we lack the observational evidence of a sufficiently high level of turbulence or strong enough magnetic fields to keep the most massive MDCs in equilibrium. If already collapsing, the observed fragmentation properties with a high core formation efficiency are consistent with the collapse setting in at parsec scales.
Key words: stars: formation / stars: massive / submillimeter: ISM
Full Table A.1 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (18.104.22.168) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/600/L10
© ESO, 2017
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