| Abstract : | Based on data from large spectroscopic surveys like the GALactic Archaeology with HERMES (GALAH) and the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST), along with astrometric and photometric data from the Gaia survey, we have addressed three major questions in the field of the chemical and dynamical evolution of the Galaxy. The first of these three questions is understanding the evolution of lithium (Li) in the Galaxy. Li in the Galaxy has increased significantly over time and the search for an explanation for such large-scale Li enrichment throughout the Galactic disc led us to study the evolution of Li in low-mass stars (the second problem we have addressed). According to the standard stellar evolutionary models, Li gets depleted as stars ascend on the red-giant branch. However, about 1% of giants have been found to have a thousandfold higher Li than the value predicted by standard models and are well known as the Li-rich giants (LRGs) and have puzzled astronomers for over four decades since their first discovery in 1982. In the process of understanding the stellar evolution of Li, we discovered 335 new LRGs and helped triple the sample of known LRGs. We also for the first time discovered the exact evolutionary phase of LRGs along with their chemical and physical properties in comparison to normal giants which helped to test and discard theories like planet engulfment and rotation-induced mixing due to binary companion as a source of Li enrichment in giants. Lastly, to uncover the formation and evolution history of the Galaxy, we studied the chemical and kinematic properties of various pro-grade and retrograde substructures in the Galactic halo along with the Galactic thin and thick disc. In this talk, I will give a brief account of the results obtained and progress made during my PhD tenure. |
