# Molecular environs and triggered star formation around the large Galactic infrared bubble N 24

## TL;DR

This study investigates the molecular environment and star formation processes around the Galactic infrared bubble N 24, revealing ongoing massive star formation likely driven by collect and collapse and radiation-driven implosion mechanisms.

## Contribution

It provides a detailed multi-wavelength analysis of N 24, identifying dense clumps and analyzing their properties to understand star formation triggers around the bubble.

## Key findings

- Detection of 23 dense clumps with masses up to 16,300 Msun
- Evidence of gravitational collapse in several clumps
- Indications of both collect and collapse and radiation-driven implosion mechanisms

## Abstract

A multi-wavelength analysis of the large Galactic infrared bubble N 24 is has been presented in this paper in order to investigate the molecular and star formation environment around expanding HII regions. Using archival data from Herschel and ATLASGAL, the distribution and physical properties of the dust over the entire bubble are studied. Twenty three dense clumps are identified using the Clumpfind2d algorithm with sizes and masses in the range 0.65-1.73 pc and 600-16300 Msun, respectively. To analyse the molecular environment in N 24, observations of NH3 (1,1) and (2,2) were carried out using the Nanshan 26m radio telescope. Analysis of the kinetic temperature and gravitational stability of these clumps suggests gravitational collapse in several of them. The mass-size distributions of the clumps and the presence of massive young protostars indicate that the shell of N 24 is a region of ongoing massive star formation. The compatibility of the dynamical and fragmentation time-scales and the overabundance of YSOs and clumps on the rim suggest that the collect and collapse mechanism is in play at the boundary of the bubble, but the existence of the IRDC at the edge of bubble indicates that radiation-driven implosion mechanism may also have played a role there.