The age of a star cannot be measured; it can only be inferred from comparing observational parameters with predictions from stellar models. Hereby, the incomplete assumptions, parameterized description of the internal stellar physics, and limited observables lead to deviations that translate into substantial uncertainties of the determined age of worse than 10%. For red giants, stars in the advanced phases of stellar evolution, such model shortcomings accumulate over the full lifetime of the star, leading to errors of up to 30% for the age estimate. Because of their luminosity, red giants are visible over galactic and even extragalactic distances. Consequently, improving the modeling of these objects significantly impacts our understanding of the evolution of larger structures these stars are embedded in, such as exoplanetary systems or galaxies, such as the Milky Way.  

The age of a star cannot be measured; it can only be inferred from comparing observational parameters with predictions from stellar models. Hereby, the incomplete assumptions, parameterized description of the internal stellar physics, and limited observables lead to deviations that translate into substantial uncertainties of the determined age of worse than 10%. For red giants, stars in the advanced phases of stellar evolution, such model shortcomings accumulate over the full lifetime of the star, leading to errors of up to 30% for the age estimate. Because of their luminosity, red giants are visible over galactic and even extragalactic distances. Consequently, improving the modeling of these objects significantly impacts our understanding of the evolution of larger structures these stars are embedded in, such as exoplanetary systems or galaxies, such as the Milky Way.  

To address the most pressing issues of state-of-the-art stellar structural models by performing detailed asteroseismic analyses of solar-like oscillators in single and binary stars, we propose a three-year project with two main work packages. For each of the WPs, we request one PostDoc to work in the PLAtoSONG project. 

WP1 is dedicated to the detailed analysis of the time series of solar-like oscillators from space photometry and ground-based spectroscopy. Combining both observing techniques provides precise knowledge of the properties of oscillation eigenmodes, which is crucial for improving the models and obtaining unprecedented accuracy of stellar ages. WP2 will capitalize on the co-evolved nature of stars in binary systems to break the model-limiting parameter degeneracies introduced by sparse observational parameters through combined evolutionary and seismic modeling of both components. We will use astrometric binaries from the ESA Gaia mission to recalibrate the asteroseismic scaling relations for an improved mass determination of solar-like oscillators. 

PLAtoSOnG capitalizes on events that occur during the projects execution that are significant for the project. The ESA PLATO mission, scheduled for launch in 2026 and in which the IAC is a significant stakeholder, will provide data for new high-value targets for asteroseismic studies of single and binary stars. The fourth data release of the ESA Gaia mission (DR4), expected in late 2025, will provide complimentary observational data to characterize the fundamental parameters and enrich the set of potential seismic calibrator targets. The research conducted in PLAtoSOnG is aligned with the main science deliverable of the forthcoming ESA PLATO (Rauer+ 2024) mission to allow the age determination of stars with an accuracy of better than 10%. 

We foresee an additional educational work package by proposing to organize an IAC Winter School on Astrophysics on the topic of PLAtoSOnG.