Rotação estelar e ambiente galáctico

Abstract

In this work, we study the distributions of rotational velocities, along with the kinematics and chemical abundances, of dwarf stars from different disk populations, in order to comprehend the relationship between these observables and the Galactic environment. The Milky Way is home to several structures, including the stellar halo, the bulge, the thin disk, and the thick disk, each inhabited by stars with unique origins and formation processes, associated with distinct chemical and kinematic properties. However, due to interactions and dynamic processes, such as radial migration, these populations mix and, as a result, our solar neighborhood is composed of stars formed at different times and in different regions of the Galaxy. As a result of the present work, utilizing chemical and rotational information, we disentangled the canonical populations of the Galactic disk and reproduce the main properties of these populations such as chemical enrichment, age, kinematics, orbital velocity gradients and the ratio of local density. Additionally, we also shed light on the origin of stellar angular momentum and the statistical nature of the distribution of projected rotational velocity, v sin i, of the disk components and demonstrate a possible spatial coupling of this observable with the Galactic environment. Our results suggest that the rotational velocities of stars are not only defined by their evolutionary processes, but also by their sites of formation. Through estimates of birth radii, we find that the entropic index q of the v sin i distributions depends on the shear of the Galaxy’s differential rotation, revealing that stellar rotation is closely linked to events unfolding on global scales. Furthermore, we observed that the rotational properties of some stars are possibly associated with the effects of the Galactic bar. Finally, our results indicate that the rotational shear of the Milky Way increases in outer regions of the disk.