Under the Vega system for measuring the brightness of astronomical brightness, the star Vega is defined to have an apparent magnitude of zero as measured through all filters, although this is only an approximation e.g. its actual brightness has been measured to be 0.03 in the V (visual) band.
Procyon is a binary star system with a bright primary component, Procyon A, having an apparent magnitude of 0.34, and a faint companion, Procyon B, at magnitude 10.7. The pair orbit each other with a period of 40.82 years along an elliptical orbit with an eccentricity of 0.407.
Achernar / ˈ eɪ k ər n ɑːr / is the name of the primary (or 'A') component of the binary system designated Alpha Eridani (α Eridani, abbreviated Alf Eri, α Eri), which is the brightest 'star' or point of light in, and lying at the southern tip of, the constellation of Eridanus, and the tenth-brightest in the night sky.