标题： 旋涡星系盘的恒星群体。II 吸收光谱指数径向分布的测量与建模 显示英文标题

标题： The stellar populations of spiral disks.II Measuring and modeling the radial distribution of absorption spectral indices

摘要： 使用基于干涉滤光片的成像技术，在NGC 4303和NGC 4535的盘面上测量了Mg2和Fe5270 Lick光谱指数的径向分布，直至较大的半径范围。 这些数据与本系列论文第一篇（Paper I）中已发表的NGC 4321的数据相结合，用于约束这些星系的化学（多相）演化模型。 由于一个恒星盘的积分光是加权于星形成率的星系历史的时间平均值，这些限制补充了通过HII区研究提供的化学梯度信息，而单独的HII区研究只能提供星系一生中累积的α元素丰度。 此处展示的观测结果与模型预测之间的吻合增强了对模型的信心，随后这些模型被用来描述星系参数（如恒星形成率、化学梯度以及恒星群体平均年龄梯度）的时间演化。 显示英文摘要

摘要： The radial distributions of the Mg2 and Fe5270 Lick spectral indices have been measured to large radial distances on the disks of NGC 4303 and NGC 4535 using an imaging technique based on interference filters. These data, added to those of NGC 4321 previously published in Paper I of this series are used to constraint chemical (multiphase) evolutionary models for these galaxies. Because the integrated light of a stellar disk is a time average over the history of the galaxy weighted by the star formation rate, these constraints complement the information on chemical gradients provided by the study of HII regions which, by themselves, can only provide the alpha-elements abundance accumulate over the life of the galaxy. The agreement between the observations and the model predictions shown here lends confidence to the models which are then used to describe the time evolution of galaxy parameters such as star formation rates, chemical gradients, and gradients in the mean age of the stellar population.