Canis Major
- Unicorn
- Hare
- Dove
- Aft deck of the ship
The constellation Canis Major and Canis Major (from Latin ' canis maior ', ' greater dog " ) is clearly visible south of the celestial equator, and southeast of the prominent Orion.
Description
The three stars of Orion's belt point directly to Sirius, the brightest star in the night sky, which also marks the southernmost corner of the Wintersechsecks. From Central Europe from the Big Dog in winter is low over the southern horizon. Through the western part of the constellation of the starry band of the Milky Way, so some interesting star clusters can be observed in the large dog pulls. Already in Helsinki or Stockholm, the southernmost part of the Great dog is no longer visible.
Mythology and History
The Big Dog is one of the 48 constellations of the ancient Greek astronomy, which have already been described by Ptolemy.
The constellation is very old. Even the Babylonians saw in him a dog, who accompanied the hunter Orion. The ancient Egyptians saw the other hand, in the constellation of their goddess Isis. The Greeks identified him with the dog of Aurora, who was said to be faster than all the others and also placed him as a hunting dog to the Orion.
The bright star Sirius had since time immemorial in all cultures a special meaning. At the time of the pharaohs his rise from about 2000 BC announced on the morning sky at the annual Nile flood, which was extremely important for the Egyptian agriculture and the survival of the people. The Greeks believed, however, that Sirius would enhance the scorching power of the sun and parch the land. His rise in the morning was the time of the heat of summer, you still called Dog Days.
Celestial objects
Stars
Sirius ( α Canis Majoris ) is characterized by an apparent brightness of -1.44 m, the brightest star in the night sky. At a distance of 8.7 light-years, it is one of the nearest stars. Sirius is a double star. It has a faint companion with a brightness of 8.7 m. It is a white dwarf, which runs around the main star in 50 years. 1845 Friedrich Wilhelm Bessel had discovered changes in the spectrum of Sirius, which referred to a companion star. However, this was only discovered in 1865 with a powerful telescope. The Sirius system is visually difficult to observe because of the difference in brightness of the two components is 10 size classes and the bright primary star outshines the companion.
The main star emits a whitish light, is of spectral type A to. He has 1.8 times the diameter and the 23- times brighter than our sun.
The origin of the name Sirius is not entirely secure. Maybe it comes from the Babylonian and means "the Glimmering ". He could also come from the language of the Sumerians and " scorching hot " mean.
The third brightest star in Canis Major δ Canis Majoris is 1600 light years away. He is a giant star of spectral type F8 and has 200 times the diameter and 20,000 times the luminosity of the sun. The proper name of δ Canis Majoris is Wezen. Wezen is of Arabic origin and means "weight".
In 2003, the Great Dog of the Milky Way, the closest galaxy, the Canis Major dwarf galaxy, discovered. As it is, however, obscured by interstellar matter in the plane of the Milky Way, it is virtually undetectable in the visible light and could only be detected with the aid of infrared telescopes.
Double stars
The second brightest star in Canis Major, Canis Majoris ε, as Sirius is a double star. With a distance of 500 light years, it is considerably farther away. The main star is a bluish, gigantic star of spectral type B2. At a distance of 8 arc seconds, a faint companion is with a brightness of 8.1 m. To monitor the system, it takes an average of 15 cm telescopic opening.
The Arabic name Adhara means " virgin".
Canis Majoris η is one of the most luminous binary stars, we know. The main star is 100,000 times more luminous than our Sun. Despite its distance of 3,200 light-years it is 2.45 m in the night sky strikingly bright He has a companion of mag 7 in 180 seconds of arc distance. The system can already be resolved with a smaller telescope in single stars.
The Arabic name Aludra also derives from " virgin" from.
The system Canis Majoris ζ can also be observed with a small telescope. The Arabic name Phurud means as much as " the lonely ".
τ CMa is a triple asterisk. The 4.5 m main bright star has two companions of the 10th and 11th magnitude. The system can be observed with a telescope of 10 cm aperture.
145 CMa, also called Herschel 3945, is a worthy object of observation. The astronomer John Herschel discovered him in 1837 from his observations at the Cape of Good Hope. In a telescope to show a golden brown and a whitish shining star. The two stars are, however, not physically, ie, bound by gravity to each other but are from Earth, viewed in a direction. It is an optical double star.
Variable Stars
Canis Majoris β ( Murzim, Arabic " herald " ), is a 715 light -years away pulsationsveränderlicher star, similar to the Cepheids. Its brightness varies regularly in every 6 hours.
The stars ο1 (2000 light years), 27 (1000 light years) and ω (500 light years) change their brightness at irregular intervals, the brightness variations are not particularly pronounced.
UW CMa is a variable star of type beta Lyra in 5,000 light -years away. Its brightness varies with a period of 4 days, 9 hours and 26 minutes between 4.8 m and 5.3 m
VY CMa is a red supergiant and one of the largest stars known.
Messier and NGC objects
On the dog, there are four open clusters and nebulae. The star cluster M 41 took the French astronomer and comet hunter Charles Messier in his catalog of nebulous objects ( Messier catalog).
M 41 can be easily found, as it is below the Sirius. It can be seen with the naked eye and was probably already known in antiquity. The cluster is about 2,500 light years away. In binoculars and small telescopes, it offers a very beautiful sight, about 40 single stars are visible. In larger telescopes about 100 stars are visible to the 13th magnitude.
NGC 2359 is a gaseous nebula about 4,000 light-years, which was discovered in 1785 by William Herschel. In a telescope it appears as a misty patch. When using an interference filter (eg UHC filter) are interesting structures visible.
NGC 2360 was discovered in 1785 by Caroline Herschel. The cluster is about 5,000 light- years away. In the central telescope it can be dissolved in about 50 single stars to 12th magnitude.
NGC 2362, discovered in 1785 by William Herschel, is 4,600 light years away. In binoculars it appears star-shaped. To him completely dissolve you need a larger telescope. The brightest star of the pile is the triple star τ CMa described above. NGC 2362 with an age of about a million years one of the youngest open clusters, we know.
Collinder 140 was discovered in 1752 by Nicolas Lacaille. It is approximately 180 light years away. In a larger binoculars about 15 single stars are visible.