Variations in the Mass Functions of Clustered and Isolated Young Stellar Objects

TL;DR

This study investigates how the mass distribution of young stars varies with their local environment, revealing that stars in denser groups tend to be more massive, with implications for star formation models.

Contribution

It provides new evidence that stellar mass functions differ between clustered and isolated environments in young star-forming regions.

Findings

Higher stellar surface density correlates with more massive stars.

Statistically significant mass differences in Taurus, IC348, and ONC.

No clear trend observed in ChaI.

Abstract

We analyze high quality, complete stellar catalogs for four young (roughly 1 Myr) and nearby (within ~300 pc) star-forming regions: Taurus, Lupus3, ChaI, and IC348, which have been previously shown to have stellar groups whose properties are similar to those of larger clusters such as the ONC. We find that stars at higher stellar surface densities within a region or belonging to groups tend to have a relative excess of more massive stars, over a wide range of masses. We find statistically significant evidence for this result in Taurus and IC348 as well as the ONC. These differences correspond to having typically a ~10 - 20% higher mean mass in the more clustered environment. Stars in ChaI show no evidence for a trend with either surface density or grouped status, and there are too few stars in Lupus3 to make any definitive interpretation. Models of clustered star formation do not typically extend to sufficiently low masses or small group sizes in order for their predictions to be tested but our results suggest that this regime is important to consider.