Issue |
A&A
Volume 689, September 2024
|
|
---|---|---|
Article Number | A74 | |
Number of page(s) | 23 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361/202450321 | |
Published online | 04 September 2024 |
ALMA-IMF
XIII. N2H+ kinematic analysis of the intermediate protocluster G353.41
1
Departamento de Astronomía, Universidad de Concepción,
Casilla 160-C,
Concepción,
Chile
e-mail: rodralvarezz@gmail.com
2
Univ. Grenoble Alpes, CNRS, IPAG,
38000
Grenoble,
France
3
Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México,
Morelia,
Michoacán
58089,
Mexico
4
SKA Observatory, Jodrell Bank,
Lower Withington,
Macclesfield
SK11 9FT,
UK
5
National Astronomical Observatory of Japan,
2-21-1 Osawa,
Mitaka, Tokyo
181-8588,
Japan
6
Astronomical Science Program, The Graduate University for Advanced Studies,
SOKENDAI, 2-21-1 Osawa,
Mitaka, Tokyo
181-8588,
Japan
7
Departments of Astronomy, University of Virginia,
Charlottesville,
VA
22904,
USA
8
Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS,
B18N, allée Geoffroy Saint-Hilaire,
33615
Pessac,
France
9
Laboratoire de Physique de l’École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité,
75005
Paris,
France
10
Observatoire de Paris, PSL University, Sorbonne Université, LERMA,
75014,
Paris,
France
11
Department of Astronomy, University of Florida,
P.O. Box 112055,
Gainesville,
FL
32611,
USA
12
Max Planck Institute for Astronomy,
Königstuhl 17,
69117
Heidelberg,
Germany
13
S. N. Bose National Centre for Basic Sciences,
Sector-III, Salt Lake,
Kolkata
700106,
India
14
Astronomy Department, Universidad de Chile,
Camino El Observatorio 1515, Las Condes,
Santiago,
Chile
15
Departament de Física Quàntica i Astrofísica (FQA), Universitat de Barcelona (UB),
Martí i Franquès 1,
08028
Barcelona,
Catalonia,
Spain
16
Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona,
Martí i Franquès, 1,
08028,
Barcelona,
Catalonia,
Spain
17
Institut d’Estudis Espacials de Catalunya (IEEC),
Gran Capità, 2–4,
08034
Barcelona, Catalonia,
Spain
18
Instituto Argentino de Radioastronomía (CCT-La Plata, CONICET; CICPBA),
C.C. No. 5, 1894, Villa Elisa,
Buenos Aires,
Argentina
19
Joint Alma Observatory (JAO),
Alonso de Córdova 3107, Vitacura,
Santiago,
Chile
20
School of Physics and Astronomy, Yunnan University,
Kunming,
650091,
PR China
21
Institute of Astronomy and Department of Physics, National Tsing Hua University,
Hsinchu
30013,
Taiwan
22
Max-Planck-Institut für Radioastronomie,
Auf dem Hü gel 69,
53121
Bonn,
Germany
Received:
10
April
2024
Accepted:
12
June
2024
The ALMA-IMF Large Program provides multi-tracer observations of 15 Galactic massive protoclusters at a matched sensitivity and spatial resolution. We focus on the dense gas kinematics of the G353.41 protocluster traced by N2H+ (1−0), with a spatial resolution of ~0.02 pc. G353.41, at a distance of ~2kpc, is embedded in a larger-scale (~8 pc) filament and has a mass of ~2.5 × 103 M⊙ within 1.3 × 1.3 pc2. We extracted the N2H+ (1−0) isolated line component and decomposed it by fitting up to three Gaussian velocity components. This allows us to identify velocity structures that are either muddled or impossible to identify in the traditional position-velocity diagram. We identify multiple velocity gradients on large (~1 pc) and small scales (~0.2pc). We find good agreement between the N2H+ velocities and the previously reported DCN core velocities, suggesting that cores are kinematically coupled with the dense gas in which they form. We have measured nine converging “V-shaped” velocity gradients (VGs) (~20 km s−1 pc−1) that are well resolved (sizes ~0.1 pc), mostly located in filaments, which are sometimes associated with cores near their point of convergence. We interpret these V-shapes as inflowing gas feeding the regions near cores (the immediate sites of star formation). We estimated the timescales associated with V-shapes as VG−1, and we interpret them as inflow timescales. The average inflow timescale is ~67 kyr, or about twice the free-fall time of cores in the same area (~33 kyr) but substantially shorter than protostar lifetime estimates (~0.5 Myr). We derived mass accretion rates in the range of (0.35–8.77) × 10−4 M⊙ yr−1. This feeding might lead to further filament collapse and the formation of new cores. We suggest that the protocluster is collapsing on large scales, but the velocity signature of collapse is slow compared to pure free-fall. Thus, these data are consistent with a comparatively slow global protocluster contraction under gravity, and faster core formation within, suggesting the formation of multiple generations of stars over the protocluster’s lifetime.
Key words: ISM: clouds / ISM: kinematics and dynamics / ISM: molecules / ISM: structure
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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