A search for mass segregation of stars and brown dwarfs in \rho\ Ophiuchi

TL;DR

This study investigates the spatial distribution of stars and brown dwarfs in rho Ophiuchi using two algorithms, finding no evidence of mass segregation despite high dust obscuration.

Contribution

It applies and compares two novel algorithms for detecting mass segregation in a star-forming region, demonstrating their effectiveness even with dust obscuration.

Findings

No evidence of mass segregation detected in rho Ophiuchi

Both algorithms are effective despite high dust obscuration

Mass segregation signatures would be detectable if present

Abstract

We apply two different algorithms to search for mass segregation to a recent observational census of the rho Ophiuchi star forming region. Firstly, we apply the Lambda_MSR method, which compares the minimum spanning tree (MST) of a chosen subset of stars to MSTs of random subsets of stars in the cluster, and determine the mass segregation ratio, Lambda_MSR. Secondly, we apply the m-Sigma method, which calculates the local stellar surface density around each star and determines the statistical significance of the average surface density for a chosen mass bin, compared to the average surface density in the whole cluster. Using both methods, we find no indication of mass segregation (normal or inverse) in the spatial distribution of stars and brown dwarfs in rho Ophiuchi. Although rho Ophiuchi suffers from high visual extinction, we show that a significant mass segregation signature would be detectable, albeit slightly diluted, despite dust obscuration of centrally located massive stars.