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 H ii 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 M _ { \odot } , respectively .
To analyse the molecular environment in N 24 , observations of NH _ { 3 } ( 1,1 ) and ( 2,2 ) were carried out using the Nanshan 26-m 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 .