ALMA-IMF

ALMA-IMF observed 15 massive protoclusters capturing multiple spectral lines and the continuum emission. Here, we focus on the massive protocluster G351.77 (~2500 M ⊙ , estimated from single-dish continuum observations) located at 2 kpc. We trace the dense gas emission and kinematics with N 2 H + (1–0) at ~4 kau resolution. We estimate an N 2 H + relative abundance of ~(1.66 ± 0.46) × 10 −10 . We decompose the N 2 H + emission into up to two velocity components, highlighting the kinematic complexity in the dense gas. By examining the position-velocity (PV) and position-position-velocity (PPV) diagrams on small scales, we observe clear inflow signatures (V-shapes) associated with 1.3 mm cores. The most prominent V-shape has a mass inflow rate of ~13.45 × 10 −4 M ⊙ yr −1 and a short timescale of ~11.42 kyr. We also observe V-shapes without associated cores. This suggests both that cores or centers of accretion exist below the 1.3 mm detection limit, and that the V-shapes may be viable tracers of very early accretion and star formation on ~4 kau scales. The large-scale PV diagram shows that the protocluster is separated into two principal velocity structures separate by ~2 km s −1 . Combined with smaller-scale DCN and H 2 CO emission in the center, we propose a scenario of larger-scale slow contraction with rotation in the center based on simple toy models. This scenario is consistent with previous lines of evidence, and leads to the new suggestion of outside-in evolution of the protocluster as it collapses. The gas depletion times implied by the V-shapes are short (~0.3 Myr), requiring either very fast cluster formation, and/or continuous mass feeding of the protocluster. The latter is possible via the Mother Filament that G351.77 is forming out of. The remarkable similarities in the properties of G351.77 and the recently published work in G353.41 indicate that many of the physical conditions inferred via the ALMA-IMF N 2 H + observations may be generic to protoclusters.

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Publication Details

Journal
Astronomy and Astrophysics
Published
2025-03-24
DOI
https://doi.org/10.1051/0004-6361/202452589
Citations
7
Primary Topic
Astronomy and Astrophysical Research
Type
article
Field-Weighted Citation Impact
8.34

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article

ALMA-IMF

M. Bonfand, Patricio Sanhueza, M. Fernandez-Lopez, N. Cunningham et al.
7 citations
Astronomy and Astrophysics
Astronomy and Astrophysical Research
8.34
article

ALMA-IMF

M. Bonfand, Patricio Sanhueza, M. Fernandez-Lopez, N. Cunningham, S. Reyes-Reyes, G. Busquet, Roberto Galván-Madrid, A. Koley, J. Braine, Adam Ginsburg, E. Redaelli, F. Motte, T. Csengeri, L. Bronfman, N. A. Sandoval-Garrido, Amelia M. Stutz, R. H. Álvarez-Gutiérrez, A. Gusdorf, Hongli Liu, Pablo García, J. Salinas, J. Di Francesco, G. Bernal-Mesina
article en
7 citations

Abstract

ALMA-IMF observed 15 massive protoclusters capturing multiple spectral lines and the continuum emission. Here, we focus on the massive protocluster G351.77 (~2500 M ⊙ , estimated from single-dish continuum observations) located at 2 kpc. We trace the dense gas emission and kinematics with N 2 H + (1–0) at ~4 kau resolution. We estimate an N 2 H + relative abundance of ~(1.66 ± 0.46) × 10 −10 . We decompose the N 2 H + emission into up to two velocity components, highlighting the kinematic complexity in the dense gas. By examining the position-velocity (PV) and position-position-velocity (PPV) diagrams on small scales, we observe clear inflow signatures (V-shapes) associated with 1.3 mm cores. The most prominent V-shape has a mass inflow rate of ~13.45 × 10 −4 M ⊙ yr −1 and a short timescale of ~11.42 kyr. We also observe V-shapes without associated cores. This suggests both that cores or centers of accretion exist below the 1.3 mm detection limit, and that the V-shapes may be viable tracers of very early accretion and star formation on ~4 kau scales. The large-scale PV diagram shows that the protocluster is separated into two principal velocity structures separate by ~2 km s −1 . Combined with smaller-scale DCN and H 2 CO emission in the center, we propose a scenario of larger-scale slow contraction with rotation in the center based on simple toy models. This scenario is consistent with previous lines of evidence, and leads to the new suggestion of outside-in evolution of the protocluster as it collapses. The gas depletion times implied by the V-shapes are short (~0.3 Myr), requiring either very fast cluster formation, and/or continuous mass feeding of the protocluster. The latter is possible via the Mother Filament that G351.77 is forming out of. The remarkable similarities in the properties of G351.77 and the recently published work in G353.41 indicate that many of the physical conditions inferred via the ALMA-IMF N 2 H + observations may be generic to protoclusters.

Astronomy and AstrophysicsVol. 696
Herzberg Institute of Astrophysics (CA), Centre National de la Recherche Scientifique (FR), European Southern Observatory (DE), Université de Bordeaux (FR), University of Concepción (CL), Yunnan University (CN), National Institutes of Natural Sciences (JP), Université Paris Cité (FR), Université Paris Sciences et Lettres (FR), Universidad Católica del Norte (CL), École Normale Supérieure - PSL (FR), University of Florida (US), Sorbonne Université (FR), Max Planck Institute for Extraterrestrial Physics (DE), Institut d'Estudis Espacials de Catalunya (ES), Laboratoire d'Astrophysique de Bordeaux (FR), Institut Català de Ciències del Clima (ES), Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères (FR), SKA Observatory (GB), Max Planck Institute for Astronomy (DE), Instituto Argentino de Radioastronomía (AR), National Astronomical Observatory of Japan (JP), National Astronomical Observatories (CN), University of Virginia (US), University of Chile (CL), Universitat de Barcelona (ES), Universidad Nacional Autónoma de México (MX), Université Grenoble Alpes (FR), Universitat Politècnica de Catalunya (ES)
National Science Foundation, Chinese Academy of Sciences South America Center for Astronomy, Consejo Nacional de Ciencia y Tecnología, Agencia Nacional de Investigación y Desarrollo, Japan Society for the Promotion of Science, Fondo Nacional de Desarrollo Científico y Tecnológico
Openalex Percentile: Top 3%
Astronomy and Astrophysical Research
8.34
DOIOpen Access PDFOpenAlex
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