The Nature and Nurture of Star Clusters

Abstract

Star clusters have hierarchical patterns in space and time, suggesting formation processes in the densest regions of a turbulent interstellar medium. Clusters also have hierarchical substructure when they are young, which makes them all look like the inner mixed parts of a pervasive stellar hierarchy. Young field stars share this distribution, presumably because some of them came from dissolved clusters and others formed in a dispersed fashion in the same gas. The fraction of star formation that ends up in clusters is apparently not constant, but may increase with interstellar pressure. Hierarchical structure explains why stars form in clusters and why many of these clusters are self-bound. It also explains the cluster mass function. Halo globular clusters share many properties of disk clusters, including what appears to be an upper cluster cutoff mass. However, halo globulars are self-enriched and often connected with dwarf galaxy streams. The mass function of halo globulars could have initially been like the power law mass function of disk clusters, but the halo globulars have lost their low mass members. The reasons for this loss are not understood. It could have happened slowly over time as a result of cluster evaporation, or it could have happened early after cluster formation as a result of gas loss. The latter model explains best the observation that the globular cluster mass function has no radial gradient in galaxies.

to be published in IAUS266: Star Clusters Basic Galactic Building Blocks Throughout Time And Space, eds. Richard de Grijs and Jacques Lepine, Cambridge University Press, 11 pages

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Cited by in corpus (10)

• The Young Star Cluster population of M51 with LEGUS: I. A comprehensive study of cluster formation and evolution
• The fractal dimension of star-forming regions at different spatial scales in M33
• Metallicity, ionization parameter, and pressure variations of HII regions in the TYPHOON spiral galaxies
• Fraction of Stars in Clusters for the LEGUS Dwarf Galaxies
• The Connection Between Galaxy Environment and the Luminosity Function Slopes of Star-Forming Regions
• The Dependence of the Hierarchical Distribution of Star Clusters on Galactic Environment
• Near-infrared spectroscopy of the massive stellar population of W51: evidence for multi-seeded star formation
• The VMC survey -- XLVII. Turbulence-Controlled Hierarchical Star Formation in the Large Magellanic Cloud
• The Dependence of Prestellar Core Mass Distributions on the Structure of the Parental Cloud
• Ages and Masses of Star Clusters in M33: a Multi-wavelength Study