Beaver extinction in part for the production of castoreum, which was used as an analgesic, anti-inflammatory, and antipyretic. Castoreum was described in the 1911 British Pharmaceutical Codex for use in dysmenorrhea and hysterical conditions (i.e. pertaining to the womb), for raising blood pressure and increasing cardiac output. The activity of castoreum has been credited to the accumulation of salicin from willow trees in the beaver's diet, which is transformed to salicylic acid and has an action very similar to aspirin. Castoreum continues to be used in perfume production. Castoreum can be used as an enhancer of vanilla, strawberry and raspberry flavorings.
Castor (star) dwarf companions are difficult to determine, but are both thought to have less than half the mass of the Sun. Castor B is an Am star, with particularly strong spectral lines of certain metals. Castor C is a variable star, classified as a BY Dra type. BY Draconis variables are cool dwarf stars which vary as they rotate due to star spots or other variations in their photospheres. The two red dwarfs of Castor C are almost identical, with masses around and luminosities less than 10% of the Sun. All the red dwarfs in the Castor system have emissions lines