出典:Wikipedia
出典:『Wikipedia』 (2011/06/30 06:13 UTC 版)
Procyon (α CMi, α Canis Minoris, Alpha Canis Minoris) is the brightest star in the constellation Canis Minor. To the naked eye, it appears to be a single star, the seventh brightest in the night sky with a visual apparent magnitude of 0.34. It is actually a binary star system, consisting of a white main sequence star of spectral type F5 IV-V, named Procyon A, and a faint white dwarf companion of spectral type DA, named Procyon B. The reason for its brightness is not its intrinsic luminosity but its closeness to the Sun; at a distance of 3.5 pc or 11.41 light years, Procyon is one of our near neighbours. Its closest neighbour is Luyten's Star, 0.34 pc or 1.11 ly away.