MEGASTAR - III. Stellar parameters and data products for DR1 late-type stars

Abstract

© The Authors 2023. This work is part of the grants I+D+i RTI2018-096188-B-I00 and PID2019-107408GB-C41, which have been funded by Ministerio de Ciencia e Innovación and Agencia Estatal de Investigación (MCIN/AEI/10.13039/501100011033). It has been also partially funded by FRACTAL, INAOE and CIEMAT. S.R.B. thanks the financial support by MCIN/AEI/10.13039/501100011033 (contract FJC 2020-045785-I) and NextGeneration EU/PRTR and MIU (UNI/551/2021) through a Margarita Salas grant. This work is based on observations made with the Gran Telescopio Canarias (GTC), installed in the Spanish Observatorio del Roque de los Muchachos, in the island of La Palma. This work is based on data obtained with MEGARA instrument, funded by European Regional Development Funds (ERDF), through Programa Operativo Canarias FEDER 2014-2020. The authors thank the support given by Dr. Antonio Cabrera and Dr. Daniel Reverte, GTC Operations Group staff, during the preparation and execution of the observations at the GTC. This research made use of Astropy (Astropy Collaboration et al. 2018), a community-developed core Python package for Astronomy. This research has made use of the SIMBAD database and the VizieR catalogue access tool, CDS, Strasbourg, France (DOI: 10.26093/cds/vizier). The original description of the VizieR service was published in A&AS 143, 23. This work has made use of data from the European Space Agency (ESA) mission Gaia (https: //www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos. esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. We are very grateful to the reviewer whose comments and suggestions have helped to improve the manuscript.MEGARA is the optical integral field and multi-object spectrograph at the Gran Telescopio Canarias. We have created MEGASTAR, an empirical library of stellar spectra obtained using MEGARA at high resolution R = 20 000 (FWHM), available in two wavelength ranges: one centered in Hα, from 6420 to 6790 Å and the other centered in the Ca ii triplet, from 8370 to 8885 Å (HR-R and HR-I VPH-grating configurations). In this work, we use MEGASTAR spectra, combination of these two short wavelength intervals, to estimate the stellar parameters namely effective temperature, surface gravity and metallicity (and their associated errors) for a sample of 351 MEGASTAR members with spectral types earlier than B2. We have applied a χ^(2) technique by comparing MEGASTAR data to theoretical stellar models. For those stars with stellar parameters derived in the literature, we have obtained a good agreement between those published parameters and ours. Besides the stellar parameters, we also provide several products like the rectified spectra, radial velocities and stellar indices for this sample of stars. In a near future, we will use MEGASTAR spectra and their derived stellar parameters to compute stellar population evolutionary synthesis models, which will contribute to a better interpretation of star clusters and galaxies spectra obtained with MEGARA.Depto. de Física de la Tierra y AstrofísicaFac. de Ciencias FísicasTRUEMinisterio de Ciencia e InnovaciónAgencia Estatal de InvestigaciónFRACTALNextGeneration EU/PRTR and MIU through a Margarita Salas grantEuropean Regional Development Funds (ERDF), through Programa Operativo Canarias FEDER 2014-2020INAOECIEMATpu