Canis Major

Canis Major (Latin for the greater dog) is one of the 88 modern constellations, and was also in Ptolemy's list of 48 constellations. It is said to represent one of the dogs following Orion the hunter (see also the constellations of Orion, Canis Minor, and Canes Venatici.) Canis Major contains Sirius, the brightest star in the night sky, and that star is part of the Winter Triangle.

Notable features

Canis Major's alpha star Sirius is the brightest star besides the Sun as seen from Earth. It is also one of the nearest. The star's name means scorching, since the summer heat occurred just after Sirius' heliacal rising. The Ancient Greeks referred to such times in the summer as dog days, as only dogs would be mad enough to go out in the heat, leading to the star being known as the Dog Star. Consequently, the constellation was named after it, as a Big Dog.

Other named stars in Canis Major (all names from Arabic):

β CMa: Murzim - "The Announcer"
γ CMa: Muliphen
δ CMa: Wezen - "The Weight"
ε CMa: Adhara - "Virgins"
ζ CMa: Furud - "Bright Single One"
η CMa: Aludra

Notable deep sky objects

There aren't many bright deep sky objects in this region of sky. The only Messier object in Canis Major is M41 (NGC 2287), an open cluster of visual magnitude 4.6. It is located about 4 degrees directly south of Sirius. M41 is roughtly 2350 light years away from Earth, contains about 8,000 stars, and is about 24 light years in diameter. It is also noted for containing a number of K-class stars.

Canis Major Dwarf is a recently-discovered dwarf galaxy orbiting the Milky Way, in the constellation.

Mythology

This constellation was known to the easterners from the time immemorial. In early European classical days, this constellation represented Laelaps, Acteon's hound; or sometimes the hound of Procris, Diana's nymph; or the one given by Aurora to Cephalus, so famed for its speed that Zeus elevated it to the sky. Most commonly, Canis Major (or perhaps just the star Sirius) is Orion's hunting dog, pursuing Lepus the hare or helping Orion fight Taurus the Bull, and is referred to in this way by Aratos, Homer and Hesiod. The ancient Greeks refer only to one dog, but by Roman times, Canis Minor appears as Orion's second dog.

Roman myth also refers to Canis Major as Custos Europae, the dog guarding Europa but failing to prevent her abduction by Jupiter in the form of a bull; and as Janitor Lethaeus, the watchdog of Hell.

Depending on the faintness of stars considered, Canis Major resembles a dog facing either above or below the ecliptic. When facing below, since Sirius was considered a dog in its own right, early Greek mythology sometimes considered it to be two headed. As such, together with the area of the sky that is deserted (now considered as the new and extremely faint constellations Camelopardalis and Lynx), and the other features of the area in the Zodiac sign of Gemini (i.e. the Milky Way, and the constellations Gemini, Orion, Auriga, and Canis Minor), this may be the origin of the myth of the cattle of Geryon, which forms one of The Twelve Labours of Herakles.

Graphic visualization

The stars of the constellation Canis Major can be connected in an alternative way, which graphically shows a dog.

Stars α Canis Majoris, ν Canis Majoris, ο¹ Canis Majoris, ε Canis Majoris, σ Canis Majoris, δ Canis Majoris, and ο² Canis Majoris form the dog's body. Alpha Canis Majoris, also known as Sirius, is of magnitude zero, whereas δ and ε Canis Majoris are of magnitude two, and ο² Canis Majoris is of magnitude three.

The big dog's front right paw is star β Canis Majoris; the dog's front left paw is the star ξ Canis Majoris; the dog's right hind paw is the star ζ Canis Majoris, and the dog's left hind paw is the star κ Canis Majoris. β Canis Majoris is of the second magnitude, whereas ζ Canis Majoris is of the third magnitude.

The big dog's tail consists of stars ω Canis Majoris and η Canis Majoris, with η Canis Majoris being of the second magnitude.

Stars ι Canis Majoris, γ Canis Majoris, and θ Canis Majoris form the dog's head. All three of these stars are of the fourth magnitude.

Reference

H. A. Rey, The Stars — A New Way To See Them. Enlarged World-Wide Edition. Houghton Mifflin, Boston, 1997. ISBN 0-395-24830-2.

Notable and named stars

brightest star in the sky
binary star
nearby
< sīrius < σείριος Brilliant
< الشعرى aš-ši’rā Sirius
< canīcula The dog

< عذارى ^{c^aðārā} (The) maidens

< الوزن al-wazn The weight

< ? al-murzim The roarer (lion)/announcer (announcing Sirius)
Beta Cephei variable

< العذرة al-^{c^uðrah} Maidenhood
Alpha Cygni variable

< فرد al-furud The solitary ones

Alpha Cygni variable

irregular variable

irregular variable

Gamma Cassiopeiae variable

< محلفين muħlifayn (The star) sworn by (by two?)

Beta Cephei variable

Beta Cephei variable

Gamma Cassiopeiae variable

member of open cluster NGC 2362
Beta Lyrae variable

binary star, component magnitudes +4.9, +5.4
27 CMa A is a spectroscopic binary
27 CMa B is a Gamma Cassiopeiae variable

Beta Cephei variable

Beta Lyrae variable

Gamma Cassiopeiae variable

long-period pulsating B-type variable star

Alpha2 Canum Venaticorum variable

BD	F	Names and other designations	Mag.	Ly away
α	9	Sirius, Alpha Canis Majoris, Dog Star, Aschere, Canicula	−1.44	8.58
ε	21	Epsilon Canis Majoris, Adhara	1.50	431
δ	25	Delta Canis Majoris, Wezen	1.83	1790
β	2	Beta Canis Majoris, Murzim, Mirza	1.98	499
η	31	Eta Canis Majoris, Aludra	2.45	3200
ζ	1	Zeta Canis Majoris, Furud	3.02	336
ο²	24	Omicron2 Canis Majoris	3.02	2600
σ	22	Sigma Canis Majoris	3.49	1220
ο¹	16	Omicron1 Canis Majoris	3.89	1980
ν²	7	Nu2 Canis Majoris	3.95	64.7
ω	28	Omega Canis Majoris	4.01	920
θ	14	Theta Canis Majoris	4.08	252
γ	23	Gamma Canis Majoris, Muliphein, Isis	4.11	402
ξ¹	4	Xi1 Canis Majoris	4.34	2050
ι	20	Iota Canis Majoris	4.36	3100
κ	13	Kappa Canis Majoris	4.36	790
τ	30	Tau Canis Majoris	4.37	3200
ν³	8	Nu3 Canis Majoris	4.42	464
	27	27 Canis Majoris, EW Canis Majoris	4.42	1580
λ	13	Lambda Canis Majoris	4.47	406
ξ²	5	Xi2 Canis Majoris	4.54	412
π	19	Pi Canis Majoris	4.66	95.3
	15	15 Canis Majoris, EY Canis Majoris	4.82	1620
	29	29 Canis Majoris, UW Canis Majoris	4.88	3000
	10	10 Canis Majoris, FT Canis Majoris	5.23	2600
	11	11 Canis Majoris	5.28	642
ν¹	6	Nu1 Canis Majoris	5.71	277
	17	17 Canis Majoris	5.80	605
	26	26 Canis Majoris, MM Canis Majoris	5.91	718
	12	12 Canis Majoris, HK Canis Majoris	6.07	668

Source: The Bright Star Catalogue, 5th Revised Ed., The Hipparcos Catalogue, ESA SP-1200

Other uses of the name

The astronomer Leslie Peltier had a dog named Canis Major.

External links

The Deep Photographic Guide to the Constellations: Canis Major

Canis Major constellation

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