Procyon

Procyon is the brightest star in the constellation Canis Minor and one of the brightest stars in the night sky. It forms part of the Winter Triangle asterism with Sirius and Betelgeuse and is readily visible from most inhabited latitudes during the northern hemisphere’s winter evenings. The name Procyon comes from the Greek prokyon, meaning “before the dog,” referring to its heliacal rising before Sirius, the Dog Star.

Procyon lies at a distance of about 11.4 light-years from the Sun. It is a binary star system consisting of Procyon A, an F-type star (spectral type F5IV–V) that is more luminous than the Sun, and a faint white-dwarf companion, Procyon B. Procyon A has an effective temperature of around 6,400 to 6,700 K, a mass near 1.4 to 1.5 solar masses, a radius about twice that of the Sun, and a luminosity roughly 6 times solar. Procyon B is a DA-type white dwarf with a mass of about 0.6 solar masses and a temperature near 7,500 to 8,000 K.

The two components orbit each other with a period of about 40.8 years and a semi-major axis of roughly 20 astronomical units. The white dwarf was identified in the 19th century, making Procyon one of the early well-studied binary systems that helped describe stellar evolution and white dwarfs.

Observationally, Procyon is visible from most of the world and is used as a reference point in calibrating bright-star observations. Its proximity and binary nature have made it a focus for studies of stellar aging and binary interactions.