Abstract

The inner regions of the Galaxy have remained hidden from view at optical wavelengths due to heavy obscuration by intervening dust clouds. Hence, we do not know the details about how the Milky Way’s different components (spiral arms/disc/bulge etc) are related, their formation history etc. One way to know the details is to survey the Galaxy in near and mid-infrared wavelengths (where the obscuring effect of dust is small) and thence to count objects at different distances, classify their stellar population membership and eventually make a map of the Milky Way. Measuring distances in the Milky Way is very difficult due to the extinction along the line of sight. However, the ubiquitous presence of stars such as the giants of the red clump is useful in estimating the distance and the extinction through tracing their presence in the near-infrared colour magnitude diagrams. This thesis has addressed the problem of estimating the extinction, the distance and the stellar populations in various lines of sight. In one direction, polarimetric observations have been carried out to obtain complementary information about the material along the line of sight.