Procyon

From Wikipedia, the free encyclopedia

This article is about the star. Procyon is also the mammalian genus to which Raccoons belong.

**Procyon A/B**
Observation data Epoch J2000
Image:Position Alpha Cmi.png The position of Procyon.
Constellation	Canis Minor
Right ascension	07h 39m 18.1/17.7s
Declination	+05° 13' 29/20"
Apparent magnitude (V)	0.34/10.7
Characteristics
Spectral type	F5 IV-V/DA
B-V color index	0.40/0.0
U-B color index	−0.01
Variable type	?
Astrometry <tr valign=top><td>Radial velocity (R_v)</td><td>−3.2 km/s</td></tr><tr valign=top><td>Proper motion (μ)</td><td> RA: −716.57 mas/yr Dec.: −1034.58 mas/yr </td></tr><tr valign=top><td>Parallax (π)</td><td>286.05 ± 0.81 mas</td></tr><tr valign=top><td>Distance</td><td>11.4 ± 0.03 ly (3.496 ± 0.01 pc)</td></tr><tr valign=top><td>Absolute magnitude (M_V)</td><td>2.65/13.04</td></tr>
Details
Mass	1.50/0.60 M_☉
Radius	1.86/0.02 R_☉
Luminosity	7.73/0.00055 L_☉
Temperature	6,650/9,700 K
Metallicity	110% Sun
Rotation
Age	1.7 × 10⁹ years
Visual binary orbit
Companion	Procyon B
Period (P)	40.82 years
Semimajor axis (a)	1.18"
Eccentricity (e)	0.36
Inclination (i)	31.9°
Node (Ω)	284.8°
Periastron epoch (T)	1967.86
Other designations
α Canis Minoris, 10 Canis Minoris, GCTP 1805.00, HR 2943, BD+05°1739, LHS 233, GJ 280, HIP 37279, GC 10277, ADS 6251, CCDM 07393+0514
Database references
SIMBAD	data

Procyon (α CMi / α Canis Minoris / Alpha Canis Minoris) is the brightest star in the constellation Canis Minor and the eighth brightest star in the nighttime sky.

Its name comes from the Greek προκύον (prokúon), meaning "before the dog", since it precedes the "Dog Star" Sirius as it travels across the sky due to Earth's rotation. (Although Procyon has a greater right ascension, it also has a more northerly declination, which means it will rise above the horizon earlier than Sirius from most northerly latitudes.) These two dog stars are referred to in the most ancient literature and were venerated by the Babylonians and the Egyptians.

It is known as 南河三(Nánhésān, the Third Star in the Southern River) in Chinese

Procyon is a vertex of the Winter Triangle.

Procyon is one of the closest stars to Earth's solar system, being only 3.5 pc or 11.41 light years away. Like Sirius, it is a binary star —the main star (Procyon A) having a faint white dwarf companion (Procyon B). Its closest neighbour is Luyten's star, 0.34 pc or 1.11 ly away.

1 Procyon A
2 Procyon B
3 See also
4 External links

[edit] Procyon A

Light variability of Sol vs. that of Procyon

Procyon A is a yellowish-white star somewhat larger and 7.5 times brighter than the Sun, of spectral type F. In fact, because it is bright even for its spectral class, it is thought to be a subgiant, meaning it has just finished fusing its hydrogen into helium and begun to expand. So far, it is not thought that the star has begun to "redden" but as it continues to expand, the star will swell to about 80 - 150 times its current diameter and become a red or orange color. This will probably happen within 10 - 100 million years. It is expected that the Sun will also go through this process when it begins to die.

In late June of 2004, Canada's orbital MOST satellite telescope completed a 32-day survey of Procyon A. The continuous optical monitoring was intended to confirm oscillations in its brightness observed from Earth. During the entire two month period however, no fluctuation in intensity whatsoever was observed. These findings have caused astrophysicists to question the accepted tenets of helioseismology, and theories of star formation.

[edit] Procyon B

Procyon B is a faint white dwarf star, with an average separation from Procyon A of about 16 times the Earth's distance from the Sun or roughly the distance between Uranus and the Sun.