Tracing the conversion of gas into stars in Young Massive Cluster Progenitors

2015/02/12 by Daniel L. Walker, D. L. Walker, S. N. Longmore +9 · 66 citations
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Cluster (spacecraft) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Molecular cloud #Physics #Population #Star cluster #Star formation #Stars #Stellar population #Stellar, planetary, and galactic studies #Virial theorem #astro-ph.GA

paper · pdf · doi:10.1093/mnras/stv300

published in Monthly Notices of the Royal Astronomical Society 449(1), 715-725 (Oxford University Press) · 12 pages, 8 figures, 1 table. Accepted by MNRAS

arxiv created 2015/02/12 · openalex publication_date 2015/03/19 · arxiv updated 2015/06/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

Whilst young massive clusters (YMCs; M gtrsim 10⁴ M _odot, age lesssim 100 Myr) have been identified in significant numbers, their progenitor gas clouds have eluded detection. Recently, four extreme molecular clouds residing within 200 pc of the Galactic centre have been identified as having the properties thought necessary to form YMCs. Here we utilise far-IR continuum data from the Herschel Infrared Galactic Plane Survey (HiGAL) and millimetre spectral line data from the Millimetre Astronomy Legacy Team 90 GHz Survey (MALT90) to determine their global physical and kinematic structure. We derive their masses, dust temperatures and radii and use virial analysis to conclude that they are all likely gravitationally bound -- confirming that they are likely YMC progenitors. We then compare the density profiles of these clouds to those of the gas and stellar components of the Sagittarius B2 Main and North proto-clusters and the stellar distribution of the Arches YMC. We find that even in these clouds -- the most massive and dense quiescent clouds in the Galaxy -- the gas is not compact enough to form an Arches-like (M = 2x10⁴ M _odot, R_eff = 0.4 pc) stellar distribution. Further dynamical processes would be required to condense the resultant population, indicating that the mass becomes more centrally concentrated as the (proto)-cluster evolves. These results suggest that YMC formation may proceed hierarchically rather than through monolithic collapse.

Citations

• The 6-GHz methanol multibeam maser catalogue - I. Galactic Centre region, longitudes 345° to 6°
• Submillimeter continuum observations of Sagittarius B2 at subarcsecond spatial resolution
• A Universal Formation Mechanism for Open and Globular Clusters in Turbulent Gas
• TRIGONOMETRIC PARALLAXES OF MASSIVE STAR-FORMING REGIONS. VI. GALACTIC STRUCTURE, FUNDAMENTAL PARAMETERS, AND NONCIRCULAR MOTIONS
• Hubble Space Telescope/NICMOS Observations of Massive Stellar Clusters near the Galactic Center
• The Lives and Deaths of Star Clusters near the Galactic Center
• On the massive stellar population of the super star cluster Westerlund 1

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• Using the Agile software development lifecycle to develop a standalone application for generating colour magnitude diagrams
• Globular clusters as the relics of regular star formation in ‘normal’ high-redshift galaxies
• Seeding the Galactic Centre gas stream: gravitational instabilities set the initial conditions for the formation of protocluster clouds
• The Survey of Water and Ammonia in the Galactic Center (SWAG): Molecular Cloud Evolution in the Central Molecular Zone
• Star Clusters Near and Far