# Formation of the young compact cluster GM 24 triggered by a cloud-cloud collision

## TL;DR

This study presents evidence that the young star cluster GM 24 formed due to a cloud-cloud collision, supported by new CO emission observations and numerical collision models, highlighting a key mechanism in high-mass star formation.

## Contribution

It provides observational and modeling evidence that cloud-cloud collision triggered the formation of the young cluster GM 24, emphasizing its role in high-mass star formation.

## Key findings

- Two velocity components are associated with GM 24.
- Complementary distribution of the two cloud components supports collision.
- Estimated collision timescale is approximately 1 million years.

## Abstract

High-mass star formation is an important step which controls galactic evolution. GM 24 is a heavily obscured star cluster including a single O9 star with more than $\sim$100 lower mass stars within a 0.3 pc radius toward $(l,b)\sim$ (350.$^{\circ}$5, 0.$^{\circ}$96), close to the Galactic min-starburst NGC 6334. We found two velocity components associated with the cluster by new observations of $^{12}$CO $J=$ 2-1 emission, whereas the cloud was previously considered to be single. We found the distribution of the two components of $5$ km s$^{-1}$ separation shows complementary distribution which fits well with each other, if a relative displacement of 3 pc is applied along the Galactic plane. A position-velocity diagram of the GM 24 cloud is explained by a model based on the numerical simulations of two colliding clouds, where an intermediate velocity component created by collision is taken into account. We estimate the collision time scale to be $\sim$Myr in projection of a relative motion titled to the line of sight by 45 degrees. The results lend further support for cloud-cloud collision as a major mechanism of high-mass star formation in the Carina-Sagittarius Arm.