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.
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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 (6,257 °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
- Computed from mass and radius
- Spectral type
- F5IV-V (yellow-white subgiant)
Motion through space
- Note
- The motion of the pair's common centre of mass, computed as the mass-weighted mean of its stars' catalogued motions.
- Proper motion
- 1.26 arcseconds per year · its drift across our sky
- SIMBAD — 2007A&A...474..653V, 2001AJ....121.2189O
- Radial velocity
- -4.5 km/s · approaching the Sun
- SIMBAD — 2007A&A...474..653V, 2001AJ....121.2189O
- Speed across our line of sight
- 20.9 km/s
- Computed from proper motion and parallax
- Speed through space, relative to the Sun
- 21.4 km/s
- Computed from proper motion, parallax and radial velocity
Orbit (around the system barycenter)
- Semi-major axis
- 4.29 AU
- From the visual-binary orbit of Bond et al. 2015 (P = 40.84 yr, a = 15 AU, e = 0.41)
- Eccentricity
- 0.407
- From the visual-binary orbit of Bond et al. 2015 (P = 40.84 yr, a = 15 AU, e = 0.41)
- Orbital period
- 40.84 years
- From the visual-binary orbit of Bond et al. 2015 (P = 40.84 yr, a = 15 AU, e = 0.41)
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 (6,257 °C)
Radiation & temperature
- Luminosity
- 2.65 × 10²⁷ W · 6.93 L☉
- Surface temperature
- 6,530 K (6,257 °C)
- Peak wavelength
- 444 nm · violet-blue light
- Computed (Wien's law) from the surface temperature
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
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