Procyon

:"This article is about the star. Procyon is also the mammalian genus to which raccoons belong. "Starbox begin
name=Procyon A/B Starbox image


caption=The position of Procyon. Starbox observe
epoch=J2000
constell=Canis Minor
ra=07h 39m 18.1/17.7s
dec=+05° 13' 29/20"
appmag_v=0.34/10.7 Starbox character
class=F5 IV-V/DA
b-v=0.40/0.0
u-b=−0.01
variable=? Starbox astrometry
radial_v=−3.2
prop_mo_ra=−716.57
prop_mo_dec=−1034.58
parallax=286.05
p_error=0.81
absmag_v=2.65/13.04 Starbox detail
mass=1.50/0.60
radius=1.86/0.02
luminosity=7.73/0.00055 | temperature=6,650/9,700
metal=110% Sun
gravity=4.0/8.0 [cite journal
author=Provencal, J. L.; Shipman, H. L.; Koester, Detlev; Wesemael, F.; Bergeron, P.
title=Procyon B: Outside the Iron Box
journal=The Astrophysical Journal | year=2002
volume=568 | issue=1 | pages=324–334
url=http://adsabs.harvard.edu/abs/2002ApJ...568..324P
accessdate=2007-06-02 | doi = 10.1086/338769 ]
rotation=
age=1.7 × 10⁹ Starbox visbin
name=Procyon B
period=40.82
axis=4.27
eccentricity=0.41
inclination=31.9
node=284.8
periastron=1967.86 Starbox catalog
names=α Canis Minoris, 10 Canis Minoris, GCTP 1805.00, HR 2943, BD+05°1739, HD 61421, LHS 233, GJ 280, HIP 37279, GC 10277, ADS 6251, CCDM 07393+0514, TD1 10647. Starbox reference
Simbad=HR+2943

Procyon (pron-en|'proʊsɪən) (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 eighth 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.

Procyon forms one of the three vertices of the Winter Triangle, along with Sirius and Betelgeuse.

ystem

Procyon A is a white star of spectral type F5; it is 1.4 times the mass, twice the diameter, and 7.5 times more luminous than the Sun. [Gatewood G. and Han I., "An astrometric study of Procyon". Astron. J., 131, 1015-1021 (2006) - February 2006. http://simbad3.u-strasbg.fr/cgi-bin/cdsbib4?2006AJ....131.1015G Accessed 2/3/07.] , [Astron. Astrophys., 413, 251-256 (2004) - January(I) 2004Kervella et al., "The diameter and evolutionary state of Procyon A. Multi-technique modeling using asteroseismic and interferometric constraints". Astron. Astrophys., 413, 251-256 (2004) - January(I) 2004 http://simbad3.u-strasbg.fr/cgi-bin/cdsbib4?2004A%26A...413..251K Accessed 2/3/07.] , [Solstation.com, "Procyon 2". http://www.solstation.com/stars/procyon2.htm Accessed 2/3/07.] . It is bright for its spectral class, suggesting that it is a "subgiant" that has completely fused its core hydrogen into helium, and begun to expand as "burning" moves outside the core. As it continues to expand, the star will eventually swell to about 80 to 150 times its current diameter and become a red or orange color. This will probably happen within 10 to 100 million years. It is expected that the Sun will also go through this process when hydrogen fusion ceases at its core.

Like Sirius B, Procyon's companion is a white dwarf that was inferred from astrometric data long before it was observed; though its orbit was known as far back as 1861, it was not visually confirmed until 1896. [Robert Burnham Jr., "Burnham's Celestial Handbook" (New York: Dover Publications Inc., 1978), p. 450.] It is even more difficult to observe from Earth than Sirius B, due to a greater apparent magnitude difference and smaller angular separation from its primary. The average separation of the two components is 15 AUs, a little less than the distance between Uranus and the Sun, though the eccentric orbit carries them as close as 9 AUs and as far as 21. [Solstation.com]

At 0.6 solar masses, Procyon B is considerably less massive than Sirius B; however, the peculiarities of degenerate matter ensure that it is larger than its more famous neighbor, with an estimated radius of ~8600 km, versus ~5800 km for Sirius B. [Provencal et al., "Procyon B: outside the iron box". Astrophys. J., 568, 324-334 (2002) - March(III) 2002 http://simbad3.u-strasbg.fr/cgi-bin/cdsbib4?2002ApJ...568..324P Accessed 2/3/07.] , [Holberg et al., "Sirius B: A New, More Accurate View". The Astrophysical Journal, 497: 935-942, 1998 April 20 http://www.journals.uchicago.edu/doi/full/10.1086/305489 Accessed 2/3/07.] With a surface temperature of 7740 K, it is also much cooler than Sirius B; this is a testament to its lesser mass and greater age.

Oscillations controversy

In late June 2004, Canada's orbital MOST satellite telescope carried out a 32-day survey of Procyon A. The continuous optical monitoring was intended to confirm solar-like oscillations in its brightness observed from Earth and to permit asteroseismology. No oscillations were detected and the authors concluded that the theory of stellar oscillations may need to be reconsidered. [Matthews, J. M. et al: "No stellar p-mode oscillations in space-based photometry of Procyon" "Nature 430:921 (2004)" http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2004Natur.430...51M&db_key=AST&data_type=HTML&format=&high=44cedd215812216] However others argued that the non-detection was consistent with published ground-based radial velocity observations of solar-like oscillations. [Bouchy, F. et al.: "Oscillations on the star Procyon" "Nature 432:7015 (2004)" http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005astro.ph.10303B&db_key=PRE&data_type=HTML&format=&high=44cedd215813511] [Bedding, T. R. et al.: "The non-detection of oscillations in Procyon by MOST: Is it really a surprise?" "Astronomy and Astrophysics, 432:L43 (2005)" http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005A%26A...432L..43B&db_key=AST]

Photometric measurements from the NASA Wide Field Infrared Explorer (WIRE) satellite from 1999 and 2000 showed evidence of granulation (convection near the surface of the star) and solar-like oscillations. [Bruntt, H. et al.: "Evidence for Granulation and Oscillations in Procyon from Photometry with the WIRE Satellite" "The Astrophysical Journal, 633:440 (2005)" http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005ApJ...633..440B&db_key=AST&nosetcookie=1] Unlike the MOST result, the variation seen in the WIRE photometry was in agreement with radial velocity measurements from the ground.

Etymology and cultural significance

Its name comes from the Greek "προκύον" ("prokyon"), 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.

References

ee also

*List of brightest stars
*List of nearest stars
*Procyon in astrology
*Procyon in fiction

External links

* [http://www.solstation.com/stars/procyon2.htm Sol Station — Procyon]