Abstract Details

Name: Avrajit Bandyopadhyay
Affiliation: ARIES, Nainital
Conference ID: ASI2021_147
Title : Study of Milky Way Halo stars and connection to globular clusters
Authors and Co-Authors : Avrajit Bandyopadhyay (Aryabhatta Research Institute of Observational Sciences, Nainital)
Abstract Type : Oral
Abstract Category : Thesis
Abstract : The thesis aims to study the chemical abundances of very metal poor Milky Way halo stars and Globular cluster stars, to understand their possible common origin. Halo stars and globular clusters belong to the oldest stellar population of the Galaxy and detailed Chemical tagging of these populations can address several intriguing problems in the area of galaxy formation and globular cluster formation and evolution. In this study, we have used low and high resolution spectroscopic abundance analysis to address the possible connection between halo stars and globular clusters. In order to achieve this, We carried out high resolution spectroscopic survey using the Hanle echelle spectrograph at 2m Himalayan Chandra telescope. We also use low resolution spectra of Halo stars and globular clusters from Sloan Digital Sky Survey (SDSS). The thesis describes detailed abundances analysis of about 50 stars, in the metallicity range of halo and Globular clusters. These are selected from bright SDSS-MARVELS pre-survey data. All these objects are newly discovered VMP or EMP stars and their detailed chemical abundances are studied for the first time in this work. The results include discovery and analysis of EMP & CEMP-no stars in the metallicity range < -3.0 and several other (~ 35) VMP stars in the metallicity range -3.0 < [Fe/H] < -2.0. We also studied Li which is found to have a similar distribution among CEMP-no and EMP stars however a subtle difference was found in the trends with heavier elements. The other interesting results of the study are the discovery of globular cluster escapees that show the typical light-element anomalies associated with second generation GC stars and several r-process enhanced stars. We also studied the nature of the progenitor populations and sites for the different classes of r-process enhanced stars. The detailed results will be presented in the talk.