The southern Galactic high mass star-forming region , G351.63-1.25 , is a H ii region-molecular cloud complex with a luminosity of \sim 2.0 \times 10 ^ { 5 } L _ { \odot } , located at a distance of 2.4 kpc from the Sun .
In this paper , we focus on the investigation of the associated H ii region , embedded cluster and the interstellar medium in the vicinity of G351.63-1.25 .
We address the identification of exciting source ( s ) as well as the census of the stellar populations , in an attempt to unfold star formation activity in this region .
The ionised gas distribution has been mapped using the Giant Metrewave Radio Telescope ( GMRT ) , India at three frequencies : 1280 , 610 and 325 MHz .
The H ii region shows an elongated morphology and the 1280 MHz map comprises six resolved high density regions encompassed by diffuse emission spanning 1.4 \times 1.0 pc ^ { 2 } .
Based on measurements of flux densities at multiple radio frequencies , the brightest ultracompact core has electron temperature T _ { e } \sim 7647 \pm 153 K and emission measure , EM \sim 2.0 \pm 0.8 \times 10 ^ { 7 } cm ^ { -6 } pc .
The zero age main-sequence ( ZAMS ) spectral type of the brightest radio core is O7.5 .
We have carried out near-infrared observations in the JHK _ { s } bands using the SIRIUS instrument on the 1.4 m Infrared Survey Facility ( IRSF ) telescope .
The near-infrared images reveal the presence of a cluster embedded in nebulous fan-shaped emission .
The log-normal slope of the K-band luminosity function of the embedded cluster is found to be \sim 0.27 \pm 0.03 and the fraction of the near-infrared excess stars is estimated to be 43 % .
These indicate that the age of the cluster is consistent with \sim 1 Myr .
Other available data of this region show that the warm ( mid-infrared ) and cold ( millimetre ) dust emission peak at different locations indicating progressive stages of star formation process .
The champagne flow model from a flat , thin molecular cloud is used to explain the morphology of radio emission with respect to the millimetre cloud and infrared brightness .