Global collapse of molecular clouds as a formation mechanism for the most massive stars

By Nicolas Peretto, G. Fuller, A. Duarte-Cabral, A. Avison, P. Hennebelle, J. Pineda, P. Andre', S. Bontemps, Fr'ed'erique Motte, N. Schneider and 1 more. 2013

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The relative importance of primordial molecular cloud fragmentation versus large-scale accretion still remains to be assessed in the context of massive core/star formation. Studying the kinematics of the dense gas surrounding massive-star progenitors can tell us the extent to which large-scale flow of material impacts the growth in mass of star-forming cores. Here we present a comprehensive dataset of the 5500(±800) M⊙ infrared dark cloud SDC335.579-0.272 (hereafter SDC335), which exhibits a network of cold, dense, parsec-long filaments. Atacama Large Millimeter Array (ALMA) Cycle 0 observations reveal two massive star-forming cores, MM1 and MM2, sitting at the centre of SDC335 where the filaments intersect. With a gas mass of 545(-385+770) M⊙ contained within a source diameter of 0.05 pc, MM1 is one of the most massive, compact protostellar cores ever observed in the Galaxy. As a whole, SDC335 could potentially form an OB cluster similar to the Trapezium cluster in Orion. ALMA and Mopra single-dish observations of the SDC335 dense gas furthermore reveal that the kinematics of this hub-filament system are consistent with a global collapse of the cloud. These molecular-line data point towards an infall velocity Vinf = 0.7( ± 0.2) km s-1, and a total mass infall rate Ṁinf ≃ 2.5(±1.0) × 10-3 M⊙ yr-1 towards the central pc-size region of SDC335. This infall rate brings 750(±300) M⊙ of gas to the centre of the cloud per free-fall time (tff = 3 × 105 yr). This is enough to double the mass already present in the central pc-size region in 3.5-1.0+2.2 × tff. These values suggest that the global collapse of SDC335 over the past million year resulted in the formation of an early O-type star progenitor at the centre of the cloud’s gravitational potential well.

Subfields: Astronomy and Astrophysics, Organic Chemistry, Physical and Theoretical Chemistry

View Paper: https://www.semanticscholar.org/paper/3b2f2fa28f9491a8a708e05dbaaba7ec29cec7df

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Citations in the corpus

Global hierarchical collapse in molecular clouds. Towards a comprehensive scenario (2019, background): “…and their internal filaments suggest that these systems are undergoing global multi-scale and multi-epoch collapse (e.g., Galván-Madrid et al. 2009; Peretto et al. 2013; Beuther et al. 2015; Liu et al. 2015, 2016b; Friesen et al. 2016; Jin et al. 2016; Hacar et al. 2017; Csengeri et al. 2017;…”
An ALMA study of the Orion Integral Filament: I. Evidence for narrow fibers in a massive cloud (2018, background): “Typically located at kpc distances, most of these massive filaments are found in hub-like associations (Myers 2009) forming dense ridges of gas (Galván-Madrid et al. 2010; Schneider et al. 2010; Henning et al. 2010; Hill et al. 2011; Hennemann et al. 2012; Peretto et al. 2013).”
SDC13 infrared dark clouds: longitudinally collapsing filaments? (2013, background): “On the high-mass side, infrared dark clouds (IRDCs) have been privileged targets (e.g. Miettinen 2012; Ragan et al. 2012; Henshaw et al. 2013; Busquet et al. 2013; Peretto et al. 2013).”