A multi-wavelength analysis of the diffuse H ii region G25.8700+0.1350

Abstract

We present a multiwavelength investigation of the HII regionG25.8700+0.1350, located in the inner part of the Galaxy. In radiocontinuum emission, the region is seen as a bright arc-shaped structure.An analysis of the HI line suggests that G25.8700+0.1350 lies at adistance of 6.5 kpc. The ionized gas is bordered by a photodissociationregion which is encircled by a molecular structure where four molecularclumps are detected. At infrared wavelengths, the region is also veryconspicuous. Given the high level of visual absorption in the region,the exciting stars should be searched for in the infrared band. In thiscontext, we found in the literature one Wolf-Rayet and one redsupergiant which, together with 37 2MASS sources candidates to be O-typestars, could be related to the origin of G25.8700+0.1350. Finally, asexpanding HII regions are hypothesized to trigger star formation, weused different infrared point source catalogues to search for youngstellar object candidates (cYSOs). A total of 45 cYSOs were identifiedprojected onto the molecular clouds.