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arXiv · 2605.25912

Gaia FGK Benchmark Stars: Impact of Spectral Resolution on Stellar Abundances

Ivanna Hernández-Araya·Claudia Aguilera-Gómez·Paula Jofré·Sara Vitali·Laia Casamiquela·Caroline Soubiran·Ulrike Heiter·Sergi Blanco-Cuaresma
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Abstract

In the era of large Milky Way spectroscopic surveys, calibrating and standardizing stellar parameters and abundance measurements is crucial. The Gaia benchmark stars (GBS) are key references points characterized by well-defined parameters derived from fundamental relations independent of spectroscopy. We analyze 30 GBS with spectra data at three different resolutions. Our goal is to evaluate the impact of spectral resolution on the measurements of the stellar parameters and chemical abundances. We also present a line selection suitable for both metal-poor and metal-rich stars. We used R~190000 (R190), R~42000 (R42), R~28 000 (R28), and R190 degraded to R28 (R190-R28) spectral data to measure abundances with synthetic fitting and equivalent widths (EW) methods, testing the needed resolution to obtain consistent results. Our comparative analysis between R28 and R190-R28 shows that gaps in wavelength coverage can lead to discrepancies in the derived stellar parameters, particularly log g. These effects are not primarily driven by resolution, but rather by the limited spectral coverage and line availability. We find overall similar abundance, emphasizing the importance of line selection for spectroscopic studies. However, some elements (e.g, Ti II, Sc II) show larger discrepancies, possibly due to blending that becomes more pronounced as resolution decreases or is HFS-sensitive. Our comparative analysis shows that the abundances for Fe I, Ni I, Ti I, and Si I present less scatter across all resolutions, including R28. Our findings indicate that for some elements, synthetic fitting and the EW method give similar abundances, especially at the highest resolution. However, we also find that the highest resolution is not always essential for chemical abundance measurements. Our results provide practical guidelines for upcoming large surveys to reconstruct the chemical history of the Milky Way.

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Ivanna Hernández-Araya, Claudia Aguilera-Gómez, Paula Jofré, Sara Vitali, Laia Casamiquela, Caroline Soubiran, Ulrike Heiter, Sergi Blanco-Cuaresma. 2026-05-25. Gaia FGK Benchmark Stars: Impact of Spectral Resolution on Stellar Abundances. https://arxiv.org/abs/2605.25912

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