Procyon A

Star

Procyon A — the eighth-brightest star in the night sky, a yellow-white star (F5IV-V) 11.5 light-years away in Canis Minor. Nearly one-and-a-half solar masses and about seven times the Sun's luminosity, it is beginning to evolve off the main sequence into a subgiant. It shows Sun-like oscillations that let astronomers sound its interior, and it has a white-dwarf companion.

Open in 3D viewSee Procyon A in the live, interactive 3D map

Key facts

Mutual orbit

40.8 Earth years

14,917 Earth days

Mass

2.94 × 10³⁰ kg

1.48 M☉

Radius

1,424,794 km

2.05× wider than the Sun

Surface temperature

6,530 K (6257 °C)

Luminosity

2.65 × 10²⁷ W

Spectral type

F5IV-V (yellow-white subgiant)

Science

Physical

Mass: 2.94 × 10³⁰ kg · 1.48 M☉
Radius: 1,424,794 km · 2.05× wider than the Sun
Density: 243 kg/m³ · 0.24× water
Spectral type: F5IV-V (yellow-white subgiant)

Orbit (around the system barycenter)

Semi-major axis: 4.29 AU
Eccentricity: 0.407
Orbital period: 40.84 years

Rotation

Note: Rotates over about 23 days; its Sun-like oscillations have periods of minutes.

Composition

By mass: A star nearly one-and-a-half times the Sun's mass, hotter and about seven times more luminous. It has largely exhausted the hydrogen in its core and is evolving into a subgiant. Like the Sun it oscillates, and those pulsations let astronomers sound its interior (asteroseismology).

Temperature

Surface: 6,530 K (6257 °C)

Radiation & temperature

Luminosity: 2.65 × 10²⁷ W · 6.93 L☉
Surface temperature: 6,530 K (6257 °C)
Peak wavelength: 444 nm · violet-blue light

Discovery & history

Method: Naked-eye star
Name: 'Procyon' is from the Greek prokyon, 'before the dog' — it rises just before Sirius, the Dog Star. As the brightest star of Canis Minor, the Lesser Dog, it is Alpha Canis Minoris.

Procyon has been a prominent star since antiquity — its name marks it as the herald of Sirius. In 1844 Friedrich Bessel deduced from its wavering motion that an unseen companion tugged it (as he had for Sirius); that faint white dwarf, Procyon B, was finally glimpsed in 1896 by John M. Schaeberle at Lick Observatory.

Images

Where to find it — in Canis Minor, the Lesser Dog (IAU constellation chart). It is an unresolved point of light; its surface has never been imaged. — IAU / Sky & Telescope, R. Sinnott & R. Fienberg (CC BY 3.0) · Wikimedia Commons

Images from open archives · credit shown per image