Abstract Details

Name: Gautam Saikia
Affiliation: Indian Institue of Science
Conference ID: ASI2020_110
Title : Study of dust characteristics in the Milky Way and nearby galaxies
Authors and Co-Authors : Gautam Saikia
Abstract Type : Oral
Abstract Category : Thesis
Abstract : In order to estimate the intrinsic properties of an astrophysical object, it becomes crucial to account for dust extinction effects at shorter wavelengths. My Ph.D. thesis was an attempt to study dust grain characteristics at various locations in the Milky Way and nearby galaxies. The first half of the thesis is focused on multi-wavelength correlation studies while the second half reports the use of different dust grain models. We begin by investigating the ultraviolet (UV) – infrared (IR) correlations in the Galaxy using archival data. By separating the locations into low (-200<|b|<200) and high (|b|<-200 to |b|>200) latitudes, we found a decreasing abundance of smaller grains towards higher latitudes, where we have proposed an extra-galactic origin for the observed emissions. The Magellanic Clouds are ideal laboratories to study dust properties and abundances owing to their nearly face-on orientation and vicinity. We have investigated the UV-IR correlations at various dust locations in the Large Magellanic Cloud (LMC) including two HII regions: N11 and 30 Doradus. In the Small Magellanic Cloud (SMC), we have probed diffuse locations with an aim to provide suitable justification for the presence/absence of the 2175 angstrom feature along different sight-lines. To complement these correlation studies, we have used Orion Nebula as a target to further investigate the dust optical properties in our Galaxy. In addition to obtaining a high value of albedo (~0.7), we have also determined the distances to individual locations in a 100-400 parsec range allowing us to construct a 3D dust map around Orion. For the final thesis work, we studied the mid-IR polarization caused by dust around young stars in the 8-13 micron range by generating composite dust grain models. This was an attempt to understand the dust composition and properties around their protoplanetary disks, which will eventually develop into planetary systems.