Modelling Long-Period Variables in the Gaia Era

Luminous red giant stars exhibit variability due to stellar pulsation, that is interconnected with uncertain processes (convection, mass loss and dust formation) and results in observable features that are strongly related to stellar properties. These so-called long-period variables (LPVs) provide us with a powerful tool to infer global stellar parameters and constrain the physics of late evolutionary phases in intermediate- and old-age stellar populations. Moreover, their period-luminosity relations represent a highly promising distance indicator. Large-scale optical microlensing surveys carried out during the last few decades made ideal laboratories out of the Magellanic Clouds to investigate the ensemble properties of LPVs with low impact from distance and interstellar extinction. Building on those results, the second data release (DR2) from the Gaia mission is providing new insight on these objects and novel methods to exploit them in the study of the evolution of stars and stellar populations. These results, together with related developments, are summarized here.