Characterizing six seismic solar analogs observed by Kepler, K2, and HERMES

¹ Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, 91191 Gif-sur-Yvette, France
² Instituto de Astrofísica de Canarias (IAC), E-38205 La Laguna, Tenerife, Spain
³ Universidad de La Laguna (ULL), Departamento de Astrofísica, E-38206 La Laguna, Tenerife, Spain
⁴ School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK
⁵ Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden
⁶ STAR Institute, Université de Liège, Liège, Belgium
⁷ Department of Astronomy, Yale University, PO Box 208101 New Haven, CT 06520-8101, USA
⁸ Center for Solar-Stellar Connections, WDRC, 9020 Brumm Trail, Golden, CO 80403, USA
⁹ Department of Astronomical Science, School of Physical Sciences, SOKENDAI, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
¹⁰ Solar Science Observatory, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
¹¹ Center for Space Science, New York University Abu Dhabi, PO Box 129188 Abu Dhabi, UAE
¹² Astronomical Institute of Charles University, V Holešovičkách 2 Prague 18000, Czech Republic
¹³ Université Paris Cité, Université Paris-Saclay, CEA, CNRS, AIM, 91191 Gif-sur-Yvette, France
¹⁴ INAF – Osservatorio Astrofisico di Catania, Via S. Sofia, 78, 95123 Catania, Italy
¹⁵ IMT Atlantique, F-29238 Brest, France
¹⁶ Ecole Centrale-Supelec, Université Paris-Saclay, 91190 Gif-sur-Yvette, France
¹⁷ ENS Paris-Saclay, Université Paris-Saclay, 91190 Gif-sur-Yvette, France
¹⁸ Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 13 March 2026
Accepted: 20 April 2026

Abstract

Solar analogs–stars that closely match the fundamental properties of the Sun–provide key benchmarks for testing stellar structure and evolution across different ages and activity levels. Their detailed characterization helps place the Sun into context within the broader population of solar-like stars. This study presents the characterization of six seismic solar analogs observed by the NASA Kepler and K2 missions. Combining asteroseismic constraints from space-based photometry with high-resolution spectroscopy and Gaia astrometry, we derived their fundamental parameters and assessed their resemblance to the Sun. Global seismic properties and individual oscillation modes were extracted from the photometric light curves, while atmospheric parameters were obtained from data collected by the High-Efficiency and High-Resolution Mercator Echelle Spectrograph (HERMES) at the Mercator telescope. Stellar modeling using seven independent stellar evolution codes yielded consistent masses, radii, and ages. These stars have masses between 0.91 and 1.04 M_⊙, radii between 0.95 and 1.08 R_⊙, and ages from about 1.8–9.1 Gyr, with typical systematic uncertainties of ±0.02 M_⊙, ±0.01 R_⊙, and ±0.7 Gyr, respectively. One star, EPIC 206064678, exhibits properties very similar to those of the Sun, with M = 1.016 ± 0.033 M_⊙, R = 0.990 ± 0.011 R_⊙, and an age of 5.40 ± 0.12 Gyr. It can therefore be considered a close solar twin, although it is slightly older and more metal-rich (0.25 ± 0.07 dex). Four targets display binarity signatures and all exhibit very low chromospheric activity. This work broadens the sample of well-characterized seismic solar analogs toward a larger sample of metallicities and ages, providing new references for comparative stellar studies and future asteroseismic investigations.