| Abstract : | Dust extinction studies in our Galaxy show that majority of the sightlines show a total-to-selective extinction ratio Rv of 3.1. However, there are other sightlines that show anomalous extinction, which is different from typical Milky Way values. These sightlines are characterized by comparatively lower or higher Rv values ranging from 1.0 to 5.5. These anomalous extinction curves have been modelled mostly using modified grain-size distributions, where these variations are attributed to grain destruction in regions of intense radiation fields, shocks and grain growth in dense regions. Another observational characteristic which depends on the grain-size distribution is the scattering intensity especially in the UV. The dust scattered radiation is observed as diffuse emission in the Galaxy with intensities ranging from a few hundred photon units at high galactic latitudes to nearly a million photon units close to star forming regions. As part of this work, we will utilise the diffuse UV maps of Murthy (2014) based on GALEX data, to study possible variations in the diffuse UV emission associated with anomalous extinction. Since the intensities also depend on the properties of the main contributing stars, we will restrict our studies to locations near B 0 to B 3-type stars alone, in order to bring out the grain-size distribution dependence. |
