Four Highly Luminous Massive Star Forming Regions in the Norma Spiral Arm II. Deep NIR imaging

TL;DR

This study uses deep near-infrared imaging to identify young stellar clusters and analyze their spatial distribution, revealing primordial mass segregation likely driven by gas interactions in massive star-forming regions.

Contribution

It provides new insights into the spatial distribution and mass segregation of young stars in massive star-forming regions using deep NIR imaging.

Findings

Identification of three YSO clusters in the Norma Spiral Arm.

Detection of primordial mass segregation in two clusters.

Evidence that gas interactions influence cluster dynamics.

Abstract

We present sensitive NIR (J, H and K) imaging observations toward four luminous massive star forming regions in the Norma Spiral Arm: G324.201+0.119, G328.307+0.432, G329.337+0.147 and G330.949-0.174. We identify three clusters of young stellar objects (YSO) based on surface density diagnostics. We also find that sources detected only in the H and K-bands and with colors corresponding to spectral types earlier than B2, are likely YSOs. We analyze the spatial distribution of stars of different masses and find signatures in two clusters of primordial mass segregation which can't be explained as due to incompleteness effects. We show that dynamic interactions of cluster members with the dense gas from the parent core can explain the observed mass segregation, indicating that the gas plays an important role in the dynamics of young clusters.