Thermodynamical studies of the condensation of dust grains in distinct astrophysical environments

Abstract

Interstellar dust grains are immensely important constituents for different physicochemical processes occurring in various astrophysical environments. These grains act as a virtual laboratory and a tool to understand the physical, chemical and kinematic characteristics of stellar environments because of their capability to preserve the pristine traces of processes experienced by them in stellar environments. In order to understand the nature and the composition of dust grains, we have developed a novel thermodynamical code to study the thermodynamics associated with the dustcondensation. The code deals with the thermodynamical equilibrium as wellas non-equilibrium condensation scenarios in various astrophysical environments. These environmentsinclude Wolf-Rayet stars, low- to intermediate-mass red giant and asymptotic giant branch stars, protoplanetary discs associated with the protostars such as thegaseous solar nebula existing in the early solar system, and the supernovae ejecta. In order to demonstrate significance of condensation calculations in a real time system, we also performed the condensation calculations for a particular star that is chosen to be a red supergiant star, Betelgeuse. Inaddition, we have also made a successful attempt to estimate the bulk dust mass budget inthe evolving Milky-Way Galaxy using a novel mass balance formalism. Along with this, we tried to understand the stellar origin of various grain constituents that could carry the isotopic signatures of the various stellar nucleosynthetic sources.The numerical modelsdeveloped in this thesis would provide useful insights into the associated thermodynamicsand thermochemistry operating in wide-range of stellar as well as planetary atmospheres. newline