High-Precision Near-Infrared Abundances of Solar Analogs in the YJ Bands

TL;DR

This study conducts a high-precision near-infrared abundance analysis of 46 solar analogs using the WINERED spectrograph, deriving elemental abundances and age relations, and providing a reference spectrum and line list for future research.

Contribution

It introduces a line-by-line, empirically calibrated approach in the YJ bands for precise elemental abundance measurements in solar analogs, including elements hard to access in optical spectra.

Findings

Derived consistent abundances with previous optical studies, residuals 0.03–0.2 dex.

Extended age–[X/Fe] relations to elements like P and K.

Found a steeper age–[P/Fe] slope than for α-elements, informing Galactic chemical evolution models.

Abstract

We present a near-infrared abundance analysis of 46 solar analogs with known ages, observed with the WINERED WIDE-mode spectrograph at a resolution of $\lambda/\Delta\lambda = 28,000$. Using an empirically calibrated, line-by-line approach in the $YJ$ bands (0.976--1.089 and 1.182--1.319~{$\mu$}m), we derive abundances for 16 elements. Despite the intrinsic weakness of near-infrared phosphorus diagnostics, the combination of five P\,{\sc i} lines yields a typical uncertainty half-width of $\sim$0.04~dex, providing an estimate of the internal precision over the solar-analog sample. For other elements, the internal precision ranges from $\sim$0.01~dex for Fe and Si to over 0.05--0.14~dex for elements with only a couple of lines available. The resulting per-object abundances for various elements are consistent with previous measurements using high-precision optical spectra with residuals of 0.03--0.2~dex depending on the element. The inferred age--[X/Fe] relations reproduce known trends for the thin disk, while extending them to elements difficult to access in the optical, including P and K. We find the slope of the age--[P/Fe] relation is steeper than that for $\alpha$ elements, which provides an empirical constraint for future modeling of Galactic phosphorus evolution. In addition, we publish a high signal-to-noise (S/N 500--1000) reference spectrum constructed by combining solar-analog spectra, together with the spectra of individual stars, and an empirically calibrated line list with per-line zero-point corrections, for future near-infrared spectroscopic studies.