Vol. 629
In section 6. Interstellar and circumstellar matter

The Gaia-ESO survey: Calibrating a relationship between age and the [C/N] abundance ratio with open clusters

Present-day, large high-resolution spectroscopic surveys provide high quality abundance measurements of chemical elements that belong to the different nucleosynthesis channels, and thus also provide constraints on stellar age. The abundance ratio [C/N] is known to be an excellent indicator of stellar age, and in this work the authors calibrate the empirical relationship between the stellar age and [C/N] using giant stars in the large sample of Galactic open star clusters observed by the Gaia-ESO and APOGEE surveys. The relationship found for these star clusters, with well determined ages, were then applied to the Galactic giant field stars in the surveys where C and N abundances were measured. This analysis of the field stars shows an age separation between thin and thick disk stars and age trends within their populations, where age increases as metallicity decreases.