The embedded clusters DBS 77, 78, 102, and 160-161, and their link with the interstellar medium

Abstract

Aims. We report on a study of the global properties of some embedded clusters that are found in the fourth quadrant of the Milky Way. We aim to clarify some issues that relate to their location in the Galaxy and their stellar formation processes. Methods. We performed BVI photometric observations in the region of DBS 77, 78, 102, 160, and 161 clusters, and infrared spectroscopy in the DBS 77 region. These were complemented with JHK data from the VVV survey combined with the 2MASS catalogue, and used mid-infrared information from the GLIMPSE catalogue. We also searched for HI data from the SGPS and PMN radio surveys, and previous spectroscopic stellar classifications. The spectroscopic and photometric information enabled us to estimate the spectral classification of the brightest stars for each of the studied regions. On the other hand, we used radio data to investigate the interstellar material parameters and the continuum sources that are probably associated with the respective stellar components. Results. We estimated the basic physical parameters of the clusters (reddening, distance, age, and initial mass function). We searched for HII regions located near to the studied clusters and we analyzed the possible links between them. In the particular case of the DBS 160-161 clusters, we identified the HI bubble B332.5-0.1-42 that is located around them. We found that the mechanical energy injected in to the interstellar medium by the more massive stars of this couple of clusters was enough to generate the bubble.