The chemical evolution of the Galactic disk through Open Clusters

Author: Laia Casamiquela


Abstract: The Galactic chemical evolution is the study of the transformation of gas into stars and the resulting evolution of the chemical composition of the Galaxy. In a simple model, initially, gas of primordial composition is progressively turned into stars, which return material that has been enriched with elements synthesized by nuclear reactions, back into the interstellar medium. The key is that different groups of chemical elements are synthetized in different stars (low or high mass, binaries,...) or events (stellar winds, supernovae type Ia or II,...), that are produced at different timescales.

In particular the ratio of abundances of alpha-elements over iron has long been used as an indirect age estimator. However, in the recent years several studies (Martig et al. 2015, Chiappini et al. 2015) have found that outside the solar circle this correlation is not always achieved. This results suggest that the chemical evolution of the Galaxy is far more complex than we thought.

Open Clusters are among the best tracers to adress this question, since they provide the most reliable ages and distances, and precise chemical abundances. We present the analisis of the first Open Cluster that falls out of this correlation between alpha abundance and age.