The fractal spatial distribution of stars in open clusters and stellar associations

TL;DR

This paper explores the fractal and radial distribution patterns of stars in open clusters and associations, examining how these structures evolve and differ from the interstellar medium's fractal nature through observational and numerical evidence.

Contribution

It provides a comprehensive review of observational and numerical studies on the fractal and radial distributions of stars in clusters, highlighting the complexity of their formation and evolution.

Findings

Young clusters often exhibit fractal star distributions.

Older clusters tend to show radial density profiles.

Some open clusters have fractal structures differing from the interstellar medium.

Abstract

The Interstellar Medium has a fractal structure, in the sense that gas and dust distribute in a hierarchical and self-similar manner. Stars in new-born cluster probably follow the same fractal patterns of their parent molecular clouds. Moreover, it seems that older clusters tend to distribute their stars with radial density profiles. Thus, it is expected that clusters form with an initial fractal distribution of stars that eventually evolves toward centrally concentrated distributions. Is this really the case? This simple picture on to the origin and early evolution of star clusters and associations is very far from being clearly understood. There can be both young clusters exhibiting radial patterns and evolved clusters showing fractal structure. Additionally, the fractal structure of some open clusters is very different from that of the Interstellar Medium in the Milky Way. Here we summarize and discuss observational and numerical evidences concerning this subject.