单词visual binary
na.: 【天】幻视双星网络: 目视双星；目视变星；可见双星
【天文学】幻视双星〔肉眼看为一单星,望远镜中看才能看出为双星〕
Binary systems in which both components can be seen are called visual binary stars.
若双星中所有成员皆可以看得到，我们便称之为目视双星。