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

Peretto, Nicolas ORCID: https://orcid.org/0000-0002-6893-602X, Fuller, G. A., Duarte Cabral, Ana ORCID: https://orcid.org/0000-0002-5259-4774, Avison, A., Hennebelle, P., Pineda, J. E., André, Ph., Bontemps, S., Motte, F., Schneider, N. and Molinari, S. 2013. Global collapse of molecular clouds as a formation mechanism for the most massive stars. Astronomy and Astrophysics 555 , A112. 10.1051/0004-6361/201321318

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Abstract

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.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Subjects:	Q Science > QB Astronomy
Uncontrolled Keywords:	stars: formation; ISM: kinematics and dynamics; ISM: clouds; stars: massive; ISM: structure
Additional Information:	Pdf uploaded in accordance with publisher's policy at http://www.sherpa.ac.uk/romeo/issn/0004-6361/ (accessed 16/04/2014)
Publisher:	EDP sciences
ISSN:	0004-6361
Date of First Compliant Deposit:	30 March 2016
Last Modified:	23 May 2023 16:50
URI:	https://orca.cardiff.ac.uk/id/eprint/51179

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