The Fractal Structure of the Young Blue Clusters and Associations in Nearby Galaxies

Abstract

It is known that the location of the stars, from young open clusters to large blue groups, follows fractal and sub-fractal patterns inherited from the original molecular clouds in the star-forming process. In this work, we compared different mock models and real observations. Also, for comparison purposes, we made mock models of non-fractal cusp clusters using different parameters to describe the star density. We also computed the Q parameter. This parameter describes the geometrical structure of object distribution and statistically quantifies the fractal substructures, distinguishing fragmented from smooth distributions. We also compared model realizations and real observations in the same way. We presented the results of measuring the Q parameter with different amounts of objects and levels of contamination by field stars. In this way, we could understand the Q value behavior in poor stellar clusters and the impact of the field stars. We compare and show a new algorithm that produces a circular symmetry instead of the box-shape type commonly used to simulate fractal structures in the astronomical context.