Abstract Details

Name: Susmitha Rani Antony
Affiliation: Tata Institute of fundamental research, Mumbai
Conference ID: ASI2020_82
Title : Chemical evolution in the early Universe- a probe using Zn-S abundance in EMP stars
Authors and Co-Authors : A. Susmitha, A. Bandyopadhyay, D.K. Ojha, T. Sivarani
Abstract Type : Oral
Abstract Category : Stars, ISM and Galaxy
Abstract : Extremely metal-poor stars (EMP) are the stellar relics from the early Universe. The abundance pattern exhibited by EMP stars indicates that they were formed when the Universe had not experienced many supernovae explosions. So their chemical abundance can be used to probe the various nucleosynthetic events that existed in the early Universe and contribution of First stars to the ISM from which subsequent stars were born. Among the elements, sulphur and zinc are interesting because of their high volatile nature. Due to this, they are not readily depleted into dust grains in the ISM. So, the sulphur and zinc abundances derived from the EMP stars, represent the abundance of the ISM from which they were born. Being the simple systems formed in redshifts z > 4-5, the abundances of EMP stars can be compared with the metal enrichment in more complex systems such as damped Lyman-alpha absorption systems. Such comparison can give details of metal enrichment in these early structures thereby providing clues on cosmic chemical evolution. Various studies have reported the abundance of Zn but the abundance of S is not vastly studied due to the unavailability of suitable lines. The S I triplet at 8694 - 8695 angstrom is weaker in lower metallicity whereas the S I triplets at 9212-9238 angstrom, though stronger even in lower metallicity, were not covered due to instrument limitation. Hanle Echelle SPectrograph mounted on Himalayan Chandra Telescope has a unique wavelength coverage from 3500 to 10500 angstrom. So we performed high-resolution observations of 10 EMP stars using HESP. In this talk, I will present the results of our studies and their possible implications for the chemical evolution in the early Universe.