A study of Cepheids in Galactic open clusters and the Cepheid period-age relation in the Gaia era
Gustavo Medina, Bertrand Lemasle, Eva K. Grebel
Classical Cepheids occurring in open clusters are key for the study of stellar populations, as both can be used as tracers of recent star formation episodes, and provide valuable tests of stellar evolution models. Such tests include the calibration of the Leavitt law, the period-age relation of Cepheids, the efficiency of cluster dissolution mechanisms, among others. Throughout the last decades, however, dedicated efforts have led to a relatively small number of reported bona fide Galactic cluster Cepheids, suggesting that the vast majority of Cepheids do not reside in clusters. In this contribution, I will present the results of an all-sky search for classical Cepheids in Galactic open clusters taking advantage of the unprecedented astrometric precision and homogeneity of recent Gaia data releases. We determine the membership of Cepheids to clusters using state-of-the-art catalogues and following a Bayesian approach, taking the spatial and kinematic information of the potential cluster-Cepheid pairs into account. With this, we are able to confirm several Cepheid-cluster associations considered in previous studies as bona-fide, and to question the established cluster membership of a handful of other associations. Additionally, we identify a considerable number of new potential cluster Cepheid candidates, mostly in recently discovered clusters. Finally, we explore the feasibility of using open clusters hosting Cepheids to empirically test the Cepheid period-age relation through the use of a semi-automated method to derive cluster ages. Together with the description of our methodology, I will discuss the implications of our findings and their impact in the current understanding of the birthplace of Cepheids, their period-age relation, the clustered Cepheid fraction in the Milky Way, and the dynamical dissolution of young clusters.