Stellar rotations and the disentanglement of the galactic thin and thick discs

Abstract

The kinematics, mean α-elements, and ages of the stars reveal two distinct disc populations observed in the Solar neighbourhood. Although several studies have been carried out to characterize abundances of chemical elements and kinematic identifications in these populations, there are few studiesthat dealt with the analysis ofstellar rotation and characteristics of populationsfocused on low-massstars of the F and G types. In this work, we propose a new approach to classify stellar populationsfrom the thin and thick disc for F and G dwarf stars by relating chemical abundance and rotation (v sin i) of these stars in the rotational–chemical–plane (v sin i–[α/Fe]–[Fe/H] plot). Our results show that the two rotational-chemical sequences disentangled, high- and low-[α/Fe] components, present properties (α-enhanced, ages, kinematics, space velocity gradients, local density ratio) closely linked to the stars of the chemically and kinematically defined as thin and thick disc components. This study has an impact on calibrations that relate ages to rotation (gyro-chronology) as well as age to chemical abundances (chemochronology), as well as sheds light on the understanding of the processes of Galactic disc formation.