Stellar population astrophysics with the TNG

Abundance analysis of nearby red giants and red clump stars: Combining high-resolution spectroscopy and asteroseismology^⋆,⋆⋆

¹ Dipartimento di Fisica e Astronomia, Università di Padova, Vicolo dell’Osservatorio 2, 35122 Padova, Italy
e-mail: nagarajbadarinarayan.vernekar@phd.unipd.it
² INAF – Ossevatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
e-mail: nagaraj.vernekar@inaf.it
³ INAF – Osservatorio di Astrofisica e Scienza dello Spazio, Via P. Gobetti 93/3, 40129 Bologna, Italy
⁴ Department of Physics and Astronomy, Università di Bologna, Via Zamboni 33, 40126 Bologna, Italy
⁵ INAF – Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi, 5, 50125 Firenze, Italy
⁶ Fundación Galileo Galilei – INAF, Rambla José Ana Fernández Pérez 7, 38712 Breña Baja, Tenerife, Spain
⁷ INAF – Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monte Porzio Catone, Italy
⁸ INAF – Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy

Received: 2 October 2023
Accepted: 15 January 2024

Abstract

Context. Asteroseismology, a powerful approach for obtaining internal structure and stellar properties, requires surface temperature and chemical composition information to determine mass and age. High-resolution spectroscopy is a valuable technique for precise stellar parameters (including surface temperature) and for an analysis of the chemical composition.

Aims. We combine spectroscopic parameters with asteroseismology to test stellar models.

Methods. Using high-resolution optical and near-IR spectra from GIARPS at the Telescopio Nazionale Galileo, we conducted a detailed spectroscopic analysis of 16 stars that were photometrically selected to be on the red giant and red clump branch. Stellar parameters and chemical abundances for light elements (Li, C, N, and F), Fe peak, α and n-capture elements were derived using a combination of equivalent widths and spectral synthesis techniques based on atomic and molecular features. Ages were determined through asteroseismic scaling relations and were compared with ages based on chemical clocks, [Y/Mg] and [C/N].

Results. The spectroscopic parameters confirmed that the stars are part of the red giant branch and red clump. Two objects, HD 22045 and HD 24680, exhibit relatively high Li abundances, and HD 24680 might be a Li-rich giant resulting from mass transfer with an intermediate-mass companion that already underwent its asymptotic giant branch phase. The stellar parameters derived from scaling different sets of relations were consistent with each other. The values based on asteroseismology for the ages agree excellently with those derived from theoretical evolutionary tracks, but they disagree with ages derived from the chemical clocks [Y/Mg] and [C/N].