Statistical fractal analysis of 25 young star clusters

Abstract

A large sample of young stellar groups is analysed aiming to investigate their clustering properties and dynamical evolution. A comparison of the Q statistical parameter, measured for the clusters, with the fractal dimension estimated for the projected clouds shows that 52% of the sample has substructures and tends to follow the theoretically expected relation between clusters and clouds, according to calculations for artificial distribution of points. The fractal statistics was also compared to structural parameters revealing that clusters having radial density profile show a trend of parameter s increasing with mean surface stellar density. The core radius of the sample, as a function of age, follows a distribution similar to that observed in stellar groups of Milky Way and other galaxies. They also have dynamical age, indicated by their crossing time that is similar to unbound associations. The statistical analysis allowed us to separate the sample into two groups showing different clustering characteristics. However, they have the same dynamical evolution, since the whole sample has been revealed as expanding objects, for which the substructures seem to have not been erased. These results are in agreement with simulations that adopt low surface densities and models under supervirial conditions.

arXiv comment11 pages, 8 figures, accepted by MNRAS

References in corpus (34)

• On the variation of the Initial Mass Function
• Embedded Clusters in Molecular Clouds
• Theoretical isochrones in several photometric systems I. Johnson-Cousins-Glass, HST/WFPC2, HST/NICMOS, Washington, and ESO Imaging Survey filter sets
• Young massive star clusters
• Trigonometric Parallaxes of Massive Star Forming Regions: VI. Galactic Structure, Fundamental Parameters and Non-Circular Motions
• New catalogue of optically visible open clusters and candidates
• The Birth Environment of the Solar System
• Spitzer Observations of NGC 1333: A Study of Structure and Evolution in a Nearby Embedded Cluster
• The statistical Analysis of Star Clusters
• Massive stars in massive clusters II: Disruption of bound clusters by photoionization
• Early Evolution of Stellar Groups and Clusters: Environmental Effects on Forming Planetary Systems
• The dynamical evolution of fractal star clusters: the survival of substructure
• Dynamical evolution of star forming regions
• The distinction between star clusters and associations
• Ionizing feedback from massive stars in massive clusters III: Disruption of partially unbound clouds
• Constraints on Massive Star Formation: Cygnus OB2 was always an Association
• Evolving structures of star-forming clusters
• The spatial distribution of stars in open clusters
• The Fractal Dimension of Projected Clouds
• Clumps and triggered star formation in ionised molecular clouds
• Importance of the Initial Conditions for Star Formation - III: Statistical Properties of Embedded Protostellar Clusters
• X-ray Star Clusters in the Carina Complex
• The nature of the young and low-mass open clusters Pismis5, vdB80, NGC1931 and BDSB96
• Spatial distribution of stars and brown dwarfs in sigma Orionis
• Imprints of feedback in young gasless clusters?
• Formation and dissolution of leaky clusters
• Towards a census of the Galactic anticentre star clusters: colour-magnitude diagram and structural analyses of a sample of 50 objects
• Statistical comparison of clouds and star clusters
• On the Origin of the Salpeter Slope for the Initial Mass Function
• Characterization of Young Stellar Clusters
• Probing the anomalous extinction of four young star clusters: the use of colour-excess, main sequence fitting and fractal analysis
• Berkeley 94 and Berkeley 96: Two Young Clusters with Different Dynamical Evolution
• The embedded cluster or association Trumpler 37 in IC1396: a search for evolutionary constraints
• Spatial differences between stars and brown dwarfs: a dynamical origin?

Cited by in corpus (18)

• Structure and mass segregation in Galactic stellar clusters
• Star formation activity and the spatial distribution and mass segregation of dense cores in the early phases of star formation
• The VMC Survey XXII. Hierarchical Star Formation in the 30 Doradus-N158-N159-N160 Star-Forming Complex
• ${\mathcal{Q}}^{+}$: Characterising the structure of young star clusters
• Phase-space structures and stellar populations in the star-forming region NGC~ 2264
• Looking for phase-space structures in star-forming regions: An MST-based methodology
• The Dependence of the Hierarchical Distribution of Star Clusters on Galactic Environment
• The Structure of the Young Star Cluster NGC 6231. II. Structure, Formation, and Fate
• On the Dispersal of Young Stellar Hierarchies
• Hierarchical star formation in nearby galaxies
• An analysis of the most distant catalogued open clusters -- Re-assessing fundamental parameters with Gaia EDR3 and $\text{ASteCA}$
• The young stellar population in NGC 247 Main properties and hierarchical clustering
• Global properties, fractality, and mass segregation in single, paired, and grouped open clusters
• A method for determining the radius of an open cluster from stellar proper motions
• NGC 2548: clumpy spatial and kinematic structure in an intermediate-age galactic cluster
• ALMAGAL VI. The spatial distribution of dense cores during the evolution of cluster-forming massive clump
• Cloud structure and young star distribution in the Dragonfish complex
• NGC 3105: A Young Cluster in the Outer Galaxy