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High-mass star formation through filamentary collapse and clump-fed accretion in G22

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Yuan, J, Li, J-Z, Wu, Y, Ellingsen, SP, Henkel, C, Wang, K, Liu, T, Liu, H-L, Zavagno, A, Ren, Z and Huang, Y-F 2018 , 'High-mass star formation through filamentary collapse and clump-fed accretion in G22' , Astrophysical Journal, vol. 852, no. 1 , pp. 1-16 , doi: 10.3847/1538-4357/aa9d40.

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Abstract

How mass is accumulated from cloud-scale down to individual stars is a key open question in understanding high-mass star formation. Here, we present the mass accumulation process in a hub-filament cloud G22 that is composed of four supercritical filaments. Velocity gradients detected along three filaments indicate that they are collapsing with a total mass infall rate of about 440 M ⊙ Myr−1, suggesting the hub mass would be doubled in six free-fall times, adding up to ~2 Myr. A fraction of the masses in the central clumps C1 and C2 can be accounted for through large-scale filamentary collapse. Ubiquitous blue profiles in HCO+ (3–2) and 13CO (3–2) spectra suggest a clump-scale collapse scenario in the most massive and densest clump C1. The estimated infall velocity and mass infall rate are 0.31 km s−1 and 7.2 × 10−4 M ⊙ yr−1, respectively. In clump C1, a hot molecular core (SMA1) is revealed by the Submillimeter Array observations and an outflow-driving high-mass protostar is located at the center of SMA1. The mass of the protostar is estimated to be 11–15 M ⊙ and it is still growing with an accretion rate of 7 × 10−5 M ⊙ yr−1. The coexistent infall in filaments, clump C1, and the central hot core in G22 suggests that pre-assembled mass reservoirs (i.e., high-mass starless cores) may not be required to form high-mass stars. In the course of high-mass star formation, the central protostar, the core, and the clump can simultaneously grow in mass via core-fed/disk accretion, clump-fed accretion, and filamentary/cloud collapse.

Item Type: Article
Authors/Creators:Yuan, J and Li, J-Z and Wu, Y and Ellingsen, SP and Henkel, C and Wang, K and Liu, T and Liu, H-L and Zavagno, A and Ren, Z and Huang, Y-F
Keywords: ISM: clouds, ISM: individual objects (G22), ISM: kinematics and dynamics, stars: formation, stars: massive
Journal or Publication Title: Astrophysical Journal
Publisher: Univ Chicago Press
ISSN: 0004-637X
DOI / ID Number: 10.3847/1538-4357/aa9d40
Copyright Information:

Copyright 2017 The American Astronomical Society

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