Resumen de Moving groups as imprints of the non-axisymetric components of the milky way
It has been shown that the effects of the bar and the spiral arms of the MW can induce kinematic groups in the local stellar velocity distribution. The aims of this 'thesis are: i) to characterise the observed moving groups, establishing observational insights into their origin, and ii) to explore to what extent we can use the kinematic imprints to constrain the large scale structure of the MW and its recent evolution. To undertake the observational study we have applied the wavelet denoising technique to a compendium of kinematic, age and $[Fe/H]$ data for more than 24000 stars of the solar neighbourhood. We find that the dominant kinematic structures in the \UVplane are the branches of Sirius, Coma Berenices, Hyades~Pleiades and Hercules. From the large spread of ages and metallicities inside them, we refuse the models that relate their origin to cluster disruption. The Hercules branch is more conspicuous in the region of inner galactocentric radius and for a region that do not take larger distances from the Sun in the direction of rotation. For Hyades-Pleiades, Coma Berenices and Sirius the more negative the $V$ component, the higher the mean metallicity. The Hercules branch does not follow this correlation and has a higher metallicity dispersion. On the other hand, we have performed test particle simulations in a flexible MW potential that is consistent with several observational constraints in order to explore the phase space available to the local stellar distribution. Our results show that the bar and the spiral arms create strong kinematic _,_, imprints on the velocity distributions. When the spiral arms and the bar act together, individual imprints of each component can be still identified in the final velocity distributions. The spiral arms crowd the kinematic region of Hercules and not only the bar as traditionally believed. The arms also induce slightly tilted kinematic branches that resemble some of the observed ones. The low angular momentum moving groups such as Arcturus can have an origin related to the bar acting on a relatively hot stellar disc, which introduces a new perspective on the interpretation of its extragalactic origin. We find that the induced stellar kinematics groups depend on the structure and dynamics of the model and on the initial conditions of our experiments. We discuss if it is currently possible to use the stellar phase space groups as constraints to the large-scale structure of the MW and its evolution.
