CHEMICAL AND DYNAMICAL EVOLUTION OF SPIRAL GALAXIES SÉBASTIEN POIRIER 1 , PASCALE JABLONKA 1 and JEAN-MICHEL ALIMI 2 Observatoire de Paris-Meudon (1: GEPI, 2: LUTH) Abstract. We investigate the consequences of the hypothesis of the secular evolution (growth of the bulge from disc material via a bar and temporal evolution of the Hubble sequence) on the chem- ical evolution of a galaxy. We present the first dynamical and chemical results of our 3D tree-SPH simulations. Keywords: spiral galaxies, galaxy evolution, tree-SPH simulation 1. Introduction Different assumptions are nowadays considered for the formation and the evolution of spiral galaxies. One of them is known as the secular evolution where a central stellar bar leads the growth of the bulge by driving large quantities of gas from the disc inward. In this scenario, the Hubble sequence has an evolutionary nature in time, as galaxies can change their morphology from a late to an early type one. During the last decade, various approaches have studied the influence of a bar on its environment. Their progress followed the changes in computational means. The first studies dealt with purely collisionless matter (stars), looking at the periodicity of families of orbits in a given barred potential. Then, N-body simu- lations (collisionless matter), partially or totally self-gravitating, showed the rapid and natural organization of stars in a barred structure. Further, numerical studies of barred potentials showed that the gas of the disc could be driven towards the galaxy central regions. All these works invoked purely dynamical arguments and criteria. We wish to address their implications on the chemical evolution of galaxies. Our approach differs from previous ones also in the fact that we do not start from a preexisting galactic structure : gas and stellar density distributions are not settled a priori. The evolution of the galaxy is followed, its formation as well. We consider a general context with a pure self-gravitating object (no fixed potential). Besides the dynamical characteristics of the galaxy, we investigate its chemical evolution by calculating the abundances and abundances ratios of a num- ber of key chemical elements in different regions of the galaxy. Astrophysics and Space Science 284: 849–852, 2003. © 2003 Kluwer Academic Publishers. Printed in the Netherlands. [ 555 ]