摘要
作为目前研究复杂恒星系统的有力工具 ,星族合成方法是建立在单星演化理论基础之上的 ,因此 ,必然有其不完善性存在 ,尤其当系统中的双星成分不容忽视时。作为演化星族合成方法的基本单元 ,简单恒星星族模型的构成即排除了双星贡献。本文中 ,我们以银河系疏散星团为简单恒星星族模板 ,构造出一系列简单恒星星族积分光谱。从中我们可以看到 :蓝离散星这类理论上主要来源于双星系统的恒星 ,对星团积分光谱的紫外及蓝端有很大影响 ,从而造成简单恒星星族积分光谱能量分布的改变。这种改变势必影响对星团年龄及其它一些物理参量的判定 ,并最终影响星族合成的结果。同时 ,若以 (B -V )色指数进行度量 ,蓝离散星对简单恒星星族积分颜色的影响可达到 30 %。工作中 ,我们选取了 2 6个年龄在1x10 1 0 ～ 6x10 1 0 年之间的疏散星团为样本进行统计研究。
Stellar population synthesis is a powerful tool for the study of complex stellar systems, which is based on the results of single star evolution theory. Although being very successful in many aspects, there are still some problems unsolved, especially when the effects of the physically interactive binary stars are prominent. As the basic building blocks of evolutionary population synthesis, single stellar population (SSP) models exclude effects of interactive binary systems. In this work, we present a series of synthesized spectra of SSPs based on photometric observations of the galactic open clusters. It is shown that blue straggler stars (BSs) in these clusters, which are considered rooted in close binary systems or collision encounters, provide a considerable amount of enhancement at the ultraviolet and blue part of the spectra. These bright blue objects will modify the integrated spectral energy distribution (ISED) of the host cluster that is usually regarded as a prototype of a SSP, and will alter the age prediction of the unresolved cluster when observed photometrically, therefore greatly influence our understandings of stellar systems when high metallicity intermediate age populations become important. When measured in (B-V) color, the uncertainty in age estimation amounts up to 30%. In this work, 26 open clusters of ages ≥ 1 Gyr are analyzed.
