Infrared studies of selected regions of the milky way

The results of a large scale near -infrared survey of small sky areas of the Milky Way containing trapezium-type star multiple systems immersed in bright and dark nebulosities or southern Herbig-Haro objects are presented. Photometric maps at wavelength 2.2 microns complemented with broad-band JHKL photometry of the majority of the sources detected and of the star members of the clusters were obtained. A number of randomly chosen comparison regions along the galactic plane were also mapped and the results were also used, with recent semi-empirical models, to determine the number of field stars expected for the program surveys. In a number of regions, mainly located in the centres of young open clusters, excesses of infrared-bright stars were found and, in many cases, these were interpreted as probable embedded stars. The infrared two-colour diagrams were studied in detail in order to: (1) obtain the values of the colour excess -ratios E(J- H) /E(H -K), E(H- K) /E(K -L) and E(J- K) /E(K -L) which represent the general reddening law at these wavelengths; and (2) differentiate between the numerous reddened "normal" late -type stars from those stars with intrinsic infrared excess. Low resolution two -micron spectra were also obtained for a limited number of sources. A short description and analysis of the results are given for each of the regions observed as well as for the most interesting individual objects detected. Most infrared sources found in the surroundings of Herbig-Haro objects appear not to be associated with these emission /reflection nebulae