There is a widespread belief according to which Argelander chose the letter R for German rot or French rouge, both meaning "red", because many variable stars known at that time appear red.
有一種普遍的看法認為阿格蘭德選擇字母R是因為德語的rot或法語的 rouge，這兩個字都有紅色的含意，而當時所知的變星多數都呈現紅色。