HIGH RESOLUTION INFRA-RED SPECTROSCOPY OF SELECTED G STARS IN THE SOLAR NEIGHBORHOOD

Year 2025, Volume: 2 Issue: 1, 11 - 20, 31.12.2025

Sena Aleyna Şentürk , Timur Şahin

Abstract

High-resolution stellar spectroscopy is a fundamental tool for determining stellar atmospheric parameters and chemical abundances. With the increasing availability of high-quality near-infrared (NIR) observations, it is important to assess the consistency of stellar parameters obtained in different spectral regions. In this study, we present comparisons of optical-NIR spectroscopic analyses of two solar analog stars, HD76151 and HD115617, based on high-resolution ESPRESSO/HARPS optical spectra and IGRINS H and K band data. The analysis is based on a newly calibrated NIR atomic line list created using the solar spectrum. This line list was first validated on the Sun and HD76151. The optical and NIR analyses for these stars yield fully consistent effective temperatures, surface gravities, and chemical abundances. This confirms the internal consistency of the methodology and demonstrates that reliable NIR abundance analyses can be obtained when supported by carefully calibrated atomic data. Applying the same confirmed methodology to HD115617 reveals different behavior. While optical spectra predict an effective temperature of Teff = 5500±140 K, NIR analysis consistently shows a higher value of Teff = 5750±140 K. This ≈250 K discrepancy has been independently verified using line depth ratio diagnostics applied in both spectral regions and has led to significantly different age estimates. Extensive atomic consistency checks based on the Sun and HD 76151 indicate that this deviation cannot be attributed to deficiencies in the line list or analysis procedure. HD115617 hosts a multiplanetary system and a debris disk. This study establishes a solar-calibrated framework for multi-wavelength stellar analysis and encourages systematic optical-NIR investigations of solar-type stars.

Keywords

Infrared Spectroscopy , Stellar Abundances , Solar-Type Stars , The Sun , Atomic Data

Supporting Institution

The Scientific and Technological Research Council of Türkiye (TÜBİTAK)

Project Number

MFAG-121F265

Thanks

This work is an output of a Master’s thesis conducted under the supervised by the second author. The study was supported by the Scientific and Technological Research Council of Türkiye (TÜBİTAK) under project number MFAG-121F265. Spectral analyses were carried out using the MOOG radiative transfer code (Sneden 1973), the iSpec framework (Blanco-Cuaresma et al. 2014), and the LIME code (Şahin 2017). We thank Park et al. (2018) for providing the publicly available IGRINS spectral library, the Gaia team for making Gaia DR3 data accessible (Gaia Collaboration 2021), and the ESO Science Archive Facility for open access to the optical spectroscopic data. The atomic line list employed in the optical spectral analyses was compiled through the dedicated efforts of the members of the High-Resolution Stellar Spectroscopy Research Group at Akdeniz University.

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