21 Canum Venaticorum
21 Canum Venaticorum is a single variable star in the northern constellation of Canes Venatici, located 277 light years away from the Sun. This object has the variable star designation BK Canum Venaticorum; 21 Canum Venaticorum is the Flamsteed designation. It is visible to the naked eye as a faint white-hued star with a baseline apparent visual magnitude of +5.14. According to Garrison et al. (1994) this is a B-type subgiant star with a stellar classification of , where the suffix notation indicates this is a Silicon star. Cowley et al. (1969) listed it with a class of , which would match an A-type main-sequence star with the ':' indicating some uncertainty in the classification. It is a marginally chemically-peculiar star with weaker than normal helium absorption lines and displaying helium line variability. The widths of the lines of ionized silicon vary with a period of . 21 Canum Venaticorum is classified as an Alpha2 Canum Venaticorum type variable star and its brightness varies by 0.04 magnitudes over a period of . It is around 201 million years old and is spinning with a relatively high projected rotational velocity of 96 km/s. The star has 2.73 times the mass of