Properties of interstellar matter and stellar population in two star-forming regions

Abstract

This study aims to compare the properties of interstellar medium in two star-forming regions with different stellar content, with and without high-mass YSOs. The first region is an extended molecular cloud surrounding five IRAS sources: 05168+3634, 05184+3635, 05177+3636, 05162+3639, and IRAS 05156+3643. The second one is a physically connected pair of ultra compact HII regions, G45.07+0.13 & G45.12+0.13, associated with IRAS 19110+1045 and IRAS 19111+1048 sources, respectively. Using these two star formation regions as an example, one can see the relationship between the initial parameters of the parent molecular cloud (hydrogen column density, dust temperature), the process of star formation itself (external triggering shock or independent condensations), and the parameters of the stellar content. High-mass YSOs were obtained only in the G45.07+0.13 & G45.12+0.13 regions, in which, apparently, the initial density of the parent molecular cloud was higher and the star formation process was initiated by an external triggering shock. In addition, in the IRAS 05168+3634 region, there is a relationship between the density of the interstellar medium and the activity of the star formation process. In those subregions, where the mass and density of the initial, parent molecular cloud is greater, the process of star formation is likely to be more active and have a longer duration. In addition, in these sub-groups, on average, the mass of stars is larger.