Hubble was able to resolve six variable stars in M31.

哈勃望远镜能分辨梅西叶星云星团表31中六颗变星。

We also describe the basic principle of white dwarf cosmochronology and its application in defining the age of the Galactic disk, globular clusters, open clusters and Galactic halo.

介绍了白矮星宇宙纪学研究原理及其在盘、球星团、疏散星团以及龄确定方面应用现。