Докладчик: Ж. Лепине (Университет Сан-Пауло, Бразилия)

Название доклада: “Химический градиент в Галактическом диске”

Краткое содержание доклада:
We first summarize the evidences that have been collected from various origins (Cepheids, open clusters, planetary nebulae, temperatures of HII regions, spectra of OB stars) which show that the gradient is more complex than a simple power law: there is a strong gradient in the central regions, a plateau and a step-like decrease. We interpret this gradient in terms of the effect of the spiral arms. The metallicity is directly connected to star-formation rate: where there is a large star formation rate, there is a large rate of type II supernova explosions and a large rate of metal enrichment. The spiral arms are the birthplace of stars and the star formation rate depends on the supply of gas to the arms. The relative velocity of the arms with respect to the galactic material is an important parameter. We present the results of a simple model which is able to explain the observed trends.