EVOLUTION OF SPIRAL GALAXIES .3. APPLICATION OF THE MULTIPHASE MODEL TO THE GALACTIC DISK

被引:97
作者
FERRINI, F
MOLLA, M
PARDI, MC
DIAZ, AI
机构
[1] UNIV AUTONOMA MADRID,DEPT FIS TEOR,E-28049 MADRID,SPAIN
[2] UNIV MILAN,DIPARTIMENTO FIS,I-20133 MILAN,ITALY
关键词
GALAXIES; ABUNDANCES; EVOLUTION; SPIRAL;
D O I
10.1086/174181
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present an application of the multiphase model of Ferrini and coworkers, developed for the solar neighborhood, to other regions of the disk of the Galaxy in order to reproduce the observed element abundance gradients. The model describes the Galaxy as a two-zone system (halo and disk) sliced into nine cylindrical concentric regions and studies the time evolution of the five populations which inhabit the Milky Way: diffuse gas, molecular clouds, low-mass (m < 4 M.) and high-mass stars, and stellar remnants. Our final aim is to reproduce the metallicity gradients that are observed in the Milky Way and in other external galaxies. We analyze the evolution of these gradients in time in order to relate their behavior to other galactic quantities such as the star formation rate and the infall rate. The model describes the Galaxy by fitting a large number of observational constraints: abundance gradients, age-metallicity relations for disk and halo, both gas and mass distributions (including radial differences in the characteristic shapes of atomic and molecular gas), and radial distribution and history of star formation rate. The time evolution of abundance gradients is computed, revealing a flattening of gradients with time. In particular, the oxygen abundance was steeper at early times as a consequence of a larger infall. Since the disk is evolving and the gas is consumed, a saturation level is reached in every ring and the gradient will decrease to a minimum value.
引用
收藏
页码:745 / 758
页数:14
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