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, the star Procyon in Canis Minor completes what is known as the Winter Triangle.
Canis Minor is a northern sky constellation that is visible to observers located between +90° and -75° of latitude. It can easily be found east of Orion, with other nearby constellations including Cancer, Gemini, Hydra, and Monoceros.
Mythology of Canis Minor
The story goes that Icarius had learned to make wine from the god of the grape harvest, Dionysus, but after Icarius offered some wine to a group of shepherds, unaware of its effects, they got intoxicated and thinking they had been poisoned, killed Icarius. After her father failed to return, Erigone set off with her faithful hound, Maera, to find him and upon discovering Icarius’ body she committed suicide from grief, while Maera jumped down a well to his own demise. Dionysus subsequently paid the heroes the ultimate honor by placing them in the heavens, with Icarius forming the stars that now describe the constellation Boötes, while Erigone became the constellation Virgo, and Maera became Canis Minor. In anger, Dionysus also sent a plague upon the Athenians in revenge which was only appeased after they instituted an annual festival in the heroes’ honor.
– Procyon (Alpha Canis Minoris) is the most luminous star in Canis Minor and the 8th brightest in the sky, with an apparent magnitude of 0.34. It is situated 11.41 light years distant, and is actually a binary system which is the 13th closest to our own sun. The system consists of the white main sequence star Procyon A, which has 1.4 solar masses and 7.5 times the Sun’s luminosity, and the white dwarf star Procyon B, which has 0.6 solar masses. The name Procyon derives from the Greek for “before the dog”, as the star rises before Sirius, the dog star, in Canis Major.
– Gomeisa (Beta Canis Minoris), the 2nd brightest star in Canis Minor, is a blue-white main sequence star situated 170 light years from our solar system. Its visual magnitude ranges between 2.48 and 2.92 because the star’s rapid rotation causes irregular luminosity variations due to an outflow of matter from the photosphere. Gomeisa’s name derives from the Arabic for “the bleary-eyed (woman).”
– Gamma Canis Minoris, the constellation’s third brightest star, is an orange-red giant star (K3III SB) situated 398 light years from the Sun with a visual magnitude of 4.34. It is a double star with an orbital period of 389 days, and is also a spectroscopic binary, meaning it appears as a single star, even with the use of a telescope.
Other stars of interest in Canis Minor includes Luyten’s Star, a red dwarf found just 12.36 light years away; and G Canis Minoris, a binary star 254 light years distant whose main component is an orange K-type giant.
Notable Deep Sky Objects
Although the Milky Way runs through much of Canis Minor, the constellation contains only a small number of deep sky objects, all of which are around 15th magnitude, thus making them extremely difficult to view in anything 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.