Abstract Details

Name: Supriyo Ghosh
Affiliation: Tata Institute of Fundamental Research
Conference ID: ASI2021_221
Title : Characterisation of cool giants from low-resolution near-infrared spectra
Authors and Co-Authors : Supriyo Ghosh (TIFR, Mumbai), D. K. Ojha (TIFR, Mumbai), and J. P. Ninan (The Pennsylvania State University, USA)
Abstract Type : Oral
Abstract Category : Stars, ISM and Galaxy
Abstract : Precise estimation of fundamental parameters (e.g. Teff, log g, [Fe/H]) is a long-standing and challenging problem in astronomy, especially for cool giants because of their molecular near-photospheric environment, however, is essential to characterise the stellar populations in the Galactic and extragalactic environments. In this presentation, we present new empirical tools for the determination of fundamental parameters for cool giants covering a wider metallicity range (-2.5 dex < [Fe/H] < +1.0 dex) than in previous works. Using fairly low-resolution near-infrared spectra (R ~ 1200), we showed that such tools are quite capable of deriving fundamental parameters (a typical accuracy of 100 K in Teff and 0.2 dex in [Fe/H]) of cool giants without any knowledge of the reddening and distance to the objects. We also found that the empirical relations based on the solar-neighborhood stars can incorporate large uncertainty in evaluation Teff for metal-poor or metal-rich stars. In addition, we will show how to deploy Bayesian inference for estimating any possible systematics between different measurement techniques in the absence of any common stars in different data sets. Furthermore, we will present the implication of our established empirical tools for deriving fundamental parameters of Kepler red-giants observed with a newly installed TANSPEC instrument on 3.6-m DOT.