On the mass segregation of stars and brown dwarfs in Taurus

TL;DR

This study introduces a new MST-based method to quantify mass segregation in the Taurus star-forming region, revealing that massive stars are inversely segregated and brown dwarfs are not segregated, contrasting with denser clusters.

Contribution

The paper presents a novel MST ratio technique for assessing mass segregation, applied to Taurus, showing unique spatial distributions of stars and brown dwarfs.

Findings

Massive stars are inversely mass segregated in Taurus.

Brown dwarfs show no significant mass segregation.

Results differ from dense clusters like Orion.

Abstract

We use the new minimum spanning tree (MST) method to look for mass segregation in the Taurus association. The method computes the ratio of MST lengths of any chosen subset of objects, including the most massive stars and brown dwarfs, to the MST lengths of random sets of stars and brown dwarfs in the cluster. This mass segregation ratio (Lambda_MSR) enables a quantitative measure of the spatial distribution of high-mass and low-mass stars, and brown dwarfs to be made in Taurus. We find that the most massive stars in Taurus are inversely mass segregated, with Lambda_MSR = 0.70 +/- 0.10 (Lambda_MSR = 1 corresponds to no mass segregation), which differs from the strong mass segregation signatures found in more dense and massive clusters such as Orion. The brown dwarfs in Taurus are not mass segregated, although we find evidence that some low-mass stars are, with an Lambda_MSR = 1.25 +/- 0.15. Finally, we compare our results to previous measures of the spatial distribution of stars and brown dwarfs in Taurus, and briefly discuss their implications.