Objectives
Determining accurate and precise stellar ages remains one of the most fundamental and challenging problems in astrophysics. Because stellar ages cannot be measured directly, they must be inferred indirectly through models, empirical relations, or physical diagnostics, each carrying intrinsic uncertainties and systematics. Yet stellar ages are essential for understanding the formation and evolution of the Milky Way, constraining cosmological timescales, and tracing the origin and evolution of planetary systems.
In the past decades, significant progress has been achieved through a wide range of complementary techniques, including isochrone fitting, asteroseismology, data-driven approaches. Each method probes different stellar populations and evolutionary stages, but none is universally applicable. Isochrone fitting becomes degenerate in evolved phases, while empirical indicators such as rotation or activity are limited to young stars. Asteroseismology provides exquisite precision for evolved stars but remains restricted to relatively small samples.
The advent of large-scale surveys and space missions such as Gaia, TESS, Kepler/K2, and the forthcoming 4MOST, WEAVE surveys and PLATO mission is transforming the field by providing unprecedented datasets that combine astrometry, spectroscopy, and time-domain information. These developments now make it possible to systematically compare different age diagnostics across large and diverse stellar populations, revealing both their power and their limitations.
At the same time, stellar ages are becoming increasingly central to multiple areas of astrophysics. In Galactic archaeology, they are key to reconstructing the formation history of the Milky Way and identifying its structural components. In extragalactic astronomy, they constrain star formation histories and chemical enrichment processes. In exoplanet science, stellar ages are essential for understanding planetary system evolution. Finally, in cosmology, the oldest stars provide a lower limit on the age of the Universe, offering an independent consistency check on cosmological models.
This symposium aims to bring together experts from stellar physics, Galactic archaeology, cosmology, exoplanet and extragalactic science to critically assess current age-dating techniques, to discuss the advantages of having stellar ages in different astrophysical contexts and to develop a unified framework for stellar age determination. A central goal is to exploit synergies between different fields of expertise to improve the accuracy and precision of stellar ages.
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IAU Code of Conduct
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