Star Constellation Facts: Canis Minor, the Smaller Dog

Star Constellation Facts: Canis Minor, the Smaller Dog

Canis Minor (“small dog”) is the 71st largest of the 88 modern constellations, but despite its diminutive stature it does contain Procyon (“before the dog”), the eighth brightest star in the night sky. In the Northern Hemisphere, the constellation is best viewed in the winter and spring time, where together with Betelgeuse in Orion, and Sirius in Canis Major, Procyon in Canis Minor completes what is known as the Winter Triangle.

Mythology of Canis Minor

In Greek mythology, the constellation Canis Minor represents one of Orion‘s hunting dogs, the other dog being depicted by the larger constellation of Canis Major. Of the many legends associated with Canis Minor, the most charming perhaps is the story about Icarius and his dog Maera. The story goes that Icarius had learned to make wine from grapes, a skill he acquired from the god of wine, Dionysus. Not knowing its effects on the human condition, Icarius offered some of the wine to some shepherds, who got intoxicated, and thinking they had been poisoned, killed Icarius. However, his dog, Maera ran for help to Erigone, Icarius’ daughter, who committed suicide from grief when she saw her fathers’ dead body. Maera, however, remained with their bodies until he too died, upon which Zeus paid him the ultimate honor of placing him in the heavens in the form of the stars that now describe the constellation, Canis Minor.

Primary Stars

Star Constellations: Canis Minor, the Smaller DogProcyon – (Alpha Canis Minoris) is the most luminous star in Canis Minor and the seventh brightest in the sky, with an apparent magnitude of 0.34. Procyon is the 13th closest binary system to the Sun, and is only 11.41 light years distant. The system consists of Procyon A with 1.4 solar masses and 7.5 times the Sun’s luminosity, and Procyon B with 0.6 solar masses at an apparent magnitude of 10.7.

Gomeisa (Beta Canis Minoris), the 2nd brightest star in Canis Minor, is a B8-type main sequence star with a Gamma Cassiopeiae variable classification. Its rapid rotation causes irregular luminosity variations due to an outflow of matter from the photosphere. At a distance of around 170 light years, Gomeisa varies in luminosity between magnitudes 2.48, and 2.92. The star’s name derives from the Arabic al-ghumaisa, which translates into “the bleary-eyed (woman)”.

Other stars in Canis Minor include Canis Minoris (Gamma Canis Minoris), G Canis Minoris, and Luyten’s Star (GJ 273).

Notable Deep Sky Objects 

Canis Minor contains a small number of deep sky objects, all of which are around 15th magnitude, which makes them extremely difficult to view in any but dark skies. The most luminous object is NGC 2485, a spiral galaxy with an apparent magnitude of 12.4, located 3.5 degrees north-east of Procyon. Its coordinates are Right Ascension 07:56:48.7, and Declination +07:28:39.

Meteor Showers

Hoping to see stray Geminids during December in 1964, KB Hindley took note of about 30 meteors that appeared to originate from the region of II Canis Minoris. Although original calculations identified the comet Nicollet-Pons (C/1821 B1), as the source, a 1970 reevaluation of the meteors’ trajectories identified the comet Mellish (D/1917 F1), as the progenitor of the meteors. A more recent investigation however, failed to establish a link between the shower and Mellish (D/1917 F1), and the origin of the shower. Best time to view the Canis Minorids is between 4-15 December, with possible peaks on the 10th and 11th of the month.