The stellar content of the infalling molecular clump G286.21+0.17

TL;DR

This study uses near-infrared imaging to analyze the stellar content and sub-structure of the massive infalling molecular clump G286.21+0.17, revealing multiple young sub-clusters and ongoing star formation processes.

Contribution

It provides new insights into the early stages of massive star cluster formation by identifying sub-structures and estimating the age and mass of the embedded stellar population.

Findings

Presence of at least three sub-clusters within the region.

Detection of near-infrared excess indicating very young stellar ages.

Evidence of multiple star formation events in the molecular core.

Abstract

The early evolution during massive star cluster formation is still uncertain. Observing embedded clusters at their earliest stages of formation can provide insight into the spatial and temporal distribution of the stars and thus probe different star cluster formation models. We present near-infrared imaging of an 8'*13'(5.4pc*8.7pc) region around the massive infalling clump G286.21+0.17(also known as BYF73). The stellar content across the field is determined and photometry is derived in order to { obtain} stellar parameters for the cluster members. We find evidence for some sub-structure (on scales less than a pc diameter) within the region with apparently at least three different sub-clusters associated with the molecular clump based on differences in extinction and disk fractions. At the center of the clump we identify a deeply embedded sub-cluster. Near-infrared excess is detected for 39-44% in the two sub-clusters associated with molecular material and 27% for the exposed cluster. Using the disk excess as a proxy for age this suggests the clusters are very young. The current total stellar mass is estimated to be at least 200 Msun. The molecular core hosts a rich population of pre-main sequence stars. There is evidence for multiple events of star formation both in terms of the spatial distribution within the star forming region and possibly from the disk frequency.