Probing seismic solar analogues through observations with the NASA Kepler space telescope and HERMES high-resolution spectrograph

TL;DR

This study combines Kepler space photometry and high-resolution spectroscopy to analyze solar analogues, revealing correlations between activity, rotation, and lithium, and validating stellar models against observations.

Contribution

It presents a comprehensive analysis of 18 solar analogues using space and ground-based data, linking stellar activity, rotation, lithium abundance, and asteroseismology, and validates stellar evolution models.

Findings

Many stars exhibit activity levels similar to the solar cycle.

A correlation exists between lithium abundance and surface rotation for fast rotators.

Solar models accurately reproduce the properties of observed solar analogues.

Abstract

Stars similar to the Sun, known as solar analogues, provide an excellent opportunity to study the preceding and following evolutionary phases of our host star. The unprecedented quality of photometric data collected by the \Kepler NASA mission allows us to characterise solar-like stars through asteroseismology and study diagnostics of stellar evolution, such as variation of magnetic activity, rotation and the surface lithium abundance. In this project, presented in a series of papers by Salabert et al. (2016a,b) and Beck et al (2016a,b), we investigate the link between stellar activity, rotation, lithium abundance and oscillations in a group of 18 solar-analogue stars through space photometry, obtained with the NASA Kepler space telescope and from currently 50+ hours of ground-based, high-resolution spectroscopy with the Hermes instrument. In these proceedings, we first discuss the selection of the stars in the sample, observations and calibrations and then summarise the main results of the project. By investigating the chromospheric and photospheric activity of the solar analogues in this sample, it was shown that for a large fraction of these stars the measured activity levels are compatible to levels of the 11-year solar activity cycle 23. A clear correlation between the lithium abundance and surface rotation was found for rotation periods shorter than the solar value. Comparing the lithium abundance measured in the solar analogues to evolutionary models with the Toulouse-Geneva Evolutionary Code (TGEC), we found that the solar models calibrated to the Sun also correctly describe the set of solar/stellar analogs showing that they share the same internal mixing physics. Finally, the star KIC 3241581 and KIC 10644353 are discussed in more detail.