The structures of embedded clusters in the Perseus, Serpens and Ophiuchus molecular clouds

TL;DR

This study analyzes the spatial structure and evolution of embedded star clusters in three molecular clouds using Spitzer data, revealing how cluster morphology relates to age, mass segregation, and turbulence.

Contribution

It provides new insights into cluster evolution, mass segregation, and the influence of turbulence on cluster structure in molecular clouds.

Findings

Older clusters are more centrally condensed than younger ones.

Mass segregation is evident in older clusters like IC348 and Serpens.

Cluster structure correlates with the turbulence level of the natal cloud.

Abstract

The young stellar population data of the Perseus, Ophiuchus and Serpens molecular clouds are obtained from the Spitzer c2d legacy survey in order to investigate the spatial structure of embedded clusters using the nearest neighbour and minimum spanning tree method. We identify the embedded clusters in these clouds as density enhancements and analyse the clustering parameter Q with respect to source luminosity and evolutionary stage. This analysis shows that the older Class 2/3 objects are more centrally condensed than the younger Class 0/1 protostars, indicating that clusters evolve from an initial hierarchical configuration to a centrally condensed one. Only IC348 and the Serpens core, the older clusters in the sample, shows signs of mass segregation (indicated by the dependence of Q on the source magnitude), pointing to a significant effect of dynamical interactions after a few Myr. The structure of a cluster may also be linked to the turbulent energy in the natal cloud as the most centrally condensed cluster is found in the cloud with the lowest Mach number and vice versa. In general these results agree well with theoretical scenarios of star cluster formation by gravoturbulent fragmentation.