The Progression of Star Formation in the Rosette Molecular Cloud

TL;DR

This study uses infrared and X-ray data to analyze star formation in the Rosette Molecular Cloud, revealing that star formation occurs mainly in dense regions and that the process is rapid and synchronized across the cloud.

Contribution

It introduces a combined analysis of YSO classification, density structure, and age progression to understand star formation in the RMC.

Findings

Star formation occurs mainly in dense, high-extinction regions.

Gas column density decreases rapidly as regions evolve.

Star formation across the RMC started roughly simultaneously.

Abstract

Using Spitzer Space Telescope and Chandra X-ray Observatory data, we identify YSOs in the Rosette Molecular Cloud (RMC). By being able to select cluster members and classify them into YSO types, we are able to track the progression of star formation locally within the cluster environments and globally within the cloud. We employ nearest neighbor method (NNM) analysis to explore the density structure of the clusters and YSO ratio mapping to study age progressions in the cloud. We find a relationship between the YSO ratios and extinction which suggests star formation occurs preferentially in the densest parts of the cloud and that the column density of gas rapidly decreases as the region evolves. This suggests rapid removal of gas may account for the low star formation efficiencies observed in molecular clouds. We find that the overall age spread across the RMC is small. Our analysis suggests that star formation started throughout the complex around the same time. Age gradients in the cloud appear to be localized and any effect the HII region has on the star formation history is secondary to that of the primordial collapse of the cloud.