Abstract and Goals

The aim of Galactic archaeology is to reconstruct the evolutionary history of the Milky Way from its present-day chemical and kinematic state. Stars are the building blocks of the Galaxy and the drivers of its chemical evolution. Moreover, stellar atmospheres have the distinctive property of preserving the chemical imprint of the birth cloud for most of a star's lifetime. Nonetheless, since stars move away from their birthplaces (a process known as radial migration), kinematics can only provide a snapshot of the current dynamical state of the Galaxy. Therefore, it is only when precise and accurate stellar ages become available that one is able to uncover the chronology of stars, ultimately allowing their birthplaces to be traced back. The resulting chrono-chemo-kinematic map can then in principle be used to dissect the Milky Way into its components (disk, bulge, bar, and halo) and to disentangle the various processes responsible for their formation and evolution.

ArqueoGal will produce the first all-sky, high-resolution chrono-chemo-kinematic map of the Milky Way disk extending beyond the solar neighborhood. This will enable us to address a number of key open questions in Galactic archaeology, namely, (i) the origin of the two chemically distinct populations of the disk, (ii) the dynamical processes leading to disk flaring, and (iii) the efficiency of radial migration across the disk. We will use luminous, red-giant stars to probe the disk into the kiloparsec regime. Seismic ages will be measured for these stars based on photometry from NASA’s TESS mission. Next, we will combine stellar ages with astrometry and kinematics from ESA’s Gaia mission, as well as chemical abundances from the APOGEE survey, prior to performing Galactic modeling calculations.

The temporal dimension brought by asteroseismology constitutes the scientific innovation aspect of this project. Furthermore, a methodological innovation will be introduced with the development of an Artificial Intelligence tool for the automated classification of stellar populations. ArqueoGal will take us beyond the state of the art by enabling the time-resolved investigation of Galactic assembly. The team is highly internationalized, interdisciplinary, and world-leading in the fields of Galactic archaeology and asteroseismology. Crucially, this project will leverage the team members’ leadership within TESS and Gaia. Moreover, ArqueoGal has the potential to build a long-lasting legacy, with implications for the science definition of the forthcoming ESA’s PLATO mission and ESO’s 4MOST survey.