球状星团Hodge11、NGC1466、NGC2257的颜色-星等图研究

A Study of the Color-magnitude Diagrams of Globular Clusters Hodge11, NGC1466, NGC2257

使用新型星族合成方法对哈勃太空望远镜在大麦哲伦云中观测到的球状星团Hodge11、NGC1466、NGC2257进行颜色-星等图研究。在不考虑观测误差的前提下,通过拟合确定出这3个星团的距离模数、色余、金属丰度、年龄、星暴次数、双星比例、恒星形成历史等参数。结果表明,这3个星团有着共同的特征:属于年老星团、平均年龄在14 Gyr以上,金属丰度都为0.000 3,都是由单次星暴产生的简单星族,几个星团均含60%左右的双星。我们发现,使用新型星族合成方法比传统星族合成方法对观测结果的拟合明显更好。

Advanced stellar population synthesis(ASPS)was used to study the color-magnitude diagrams of globular clustersHodge11,NGC1466,and NGC2257,which were observed by the Hubble Space Telescope(HST)in the Large Magellanic Cloud.Without the consideration of errors in the observation,the distance modulus,color excess,metallicity,age,star burst number,binaryfraction,and star formation history of clusters were determined through fitting.The result shows that the three star clusters are old(withaverage age of more than14Gyr),and of a metallicity Z of0.0003.All of them are shown to be like single stellar populations and haveabout60percent binaries.It is shown that ASPS fits to the observations better than traditional models.