Big dog
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Great Dog constellation |
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| Latin name | Canis Major |
| Latin genitive | Canis Majoris |
| Abbreviation | CMa |
| Right ascension | 06 h 11 m 36 s to 07 h 27 m 54 s |
| declination | −33 ° 15 ′ 02 ″ to −11 ° 01 ′ 49 ″ |
| surface | 380.118 deg² rank 43 |
| Completely visible | 57.0 ° N to 90 ° S |
| Observation time for Central Europe | winter |
| Number of stars brighter than 3 mag | 5 |
| Brightest star (size) | Sirius (-1.44) |
| Meteor streams |
no |
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Neighboring constellations ( clockwise from north ) |
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| swell | IAU , |
 From the star atlas by Johann Elert Bode from 1782 |
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The constellation Big Dog ( Latin / technical language Canis Major - bigger dog ) is clearly visible south of the celestial equator and southeast of the striking Orion .
description
The three stars of the Orion belt point directly to Sirius , the brightest star in the night sky, which also marks the southernmost corner of the winter hexagon . From Central Europe, the Big Dog stands low over the southern horizon in winter. The star-rich band of the Milky Way runs through the western part of the constellation , so some interesting star clusters can be observed in the Big Dog . The southernmost part of the Big Dog is no longer visible in Helsinki or Stockholm .
Mythology and history
The big dog is one of the 48 constellations in Greek astronomy that were already described by Ptolemy .
Written evidence of the constellation is very old. Even the Babylonians saw it as a dog accompanying the hunter Orion. The ancient Egyptians , however, saw their goddess Isis or the god Anubis in the constellation . The Greeks identified him with the dog of the aurora , which is said to have been faster than all others, and also assigned him as a hunting dog to Orion .
The bright star Sirius has always had a special meaning in all cultures. During the times of the pharaohs , its rise was announced from around 2000 BC. The annual flood of the Nile in the morning sky , which was extremely important for Egyptian agriculture and the survival of the people. The Greeks believed, however, that Sirius would increase the scorching power of the sun and dry up the land. It rises in the morning at the time of the greatest summer heat, which is still called dog days today .
Celestial objects
Stars
| B. | F. | Names or other designations | Apparent brightness likes | Lj | Spectral class |
|---|---|---|---|---|---|
| α | 9 | Sirius , ashtray, canicula, dog star | −1.5 | 8.7 | A1 V |
| ε | 21st | Adhara | 1.50 | 431 | B2 III |
| δ | 25th | Wezen , Alwazn | 1.83 | 1600 | F8 Ia |
| β | 2 | Murzim , Mirzam, Mirza | 1.98 | 715 | B1 II |
| η | 31 | Aludra , | 2.45 | 3200 | B5 Ia |
| ζ | 1 | Phurud , Furud | 3.02 | 330 | |
| ο 2 | 24 | 3.02 | 2500 | B3 Ia | |
| σ | 22nd | 3.49 | 1500 | K8 Ib | |
| ο 1 | 16 | 3.89 | 2000 | K3 Ia | |
| ν 2 | 7th | 3.95 | 80 | K1 III | |
| ω | 28 | 4.01 | 500 | B3 IV | |
| θ | 14th | 4.08 | 200 | K4 III | |
| γ | 23 | Muliphein | 4.11 | about 440 | B8 II |
| ξ 1 | 4th | 4.34 | |||
| ι | 20th | 4.36 | |||
| κ | 13 | 4.36 | 800 | B2 IV | |
| τ | 30th | 4.37 | |||
| ν 3 | 8th | 4.42 | |||
| 27 | EW CMa | 4.42 | 1000 | B3 III | |
| λ | 4.47 | ||||
| ξ 2 | 5 | 4.54 | |||
| π | 19th | 4.66 | |||
| 15th | 4.82 | ||||
| 29 | UW CMa | 4.88 | |||
| μ | 18th | 5.0 | 500 | G3 III |
Sirius (α Canis Majoris) is the brightest star in the night sky with an apparent magnitude of −1.44. At a distance of 8.7 light years , it is one of the closest stars. Sirius is a double star . It has a faint companion with a brightness of 8.7 mag. It is a white dwarf that will orbit the main star in 50 years. As early as 1845, Friedrich Wilhelm Bessel had discovered changes in the spectrum of Sirius that indicated a companion star. However, this could not be discovered until 1865 with a powerful telescope . The Sirius system is visually difficult to observe, as the difference in brightness between the two components is 10 size classes and the bright main star outshines the companion.
The main star emits a whitish light and belongs to the spectral class A. It has 1.8 times the diameter and 23 times the luminosity of our sun .
The origin of the name Sirius is not entirely certain. Possibly it comes from the Babylonian and means "the glimmering". It could also come from the Sumerian language and mean "scorching hot".
The third brightest star in the Big Dog, δ Canis Majoris , is 1,600 light years away. It is a giant star of the spectral class 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 closest galaxy to the Milky Way, the Canis Major Dwarf Galaxy , was discovered in the Big Dog . However, since it is obscured by interstellar matter in the plane of the Milky Way, it is practically invisible in visible light and could only be discovered with the help of infrared telescopes.
Double stars
| object | Apparent brightness likes | Spectral classes | distance |
|---|---|---|---|
| α | −1.44 / 8.7 | B2 / A3 | 10 " |
| ε | 1.5 / 7.5 | B2 III | 176 " |
| η | 2.45 / 7.0 | B5 / A0 | 180 " |
| ζ | 3.0 / 7.6 | B3 / K0 | 176 " |
| τ | 4.5 / 10/11 | 8.2 / 14.5 | |
| 145 CMa (Herschel 3945) | 4.7 / 6.5 | K5 / F0 | 7.6 " |
The second brightest star in the Big Dog, ε Canis Majoris , is like Sirius a double star. However, at a distance of 500 light years, it is much further away. The main star is a bluish, giant star of the spectral class B2. At a distance of 8 arc seconds there is a faint companion with a brightness of 8.1 mag. To observe the system, you need a medium-sized telescope with an opening of 15 cm or more.
The Arabic name Adhara means "virgin".
η Canis Majoris is one of the brightest double stars we know. The main star is 100,000 times more luminous than our sun. Despite its distance of 3200 light years it is remarkably bright at 2.45 mag in the night sky. It has a companion of the 7th magnitude at adistance of180 arcseconds . The system can be resolved into single stars with a smaller telescope.
The Arabic name Aludra is also derived from "virgin".
The ζ Canis Majoris system can also be observed with a smaller telescope. The Arabic name Phurud means something like "the lonely".
τ CMa is a triple star. The 4.5 mag bright main star has two companions of the 10th and 11th magnitude. The system can be observed with a telescope from an opening of 10 cm.
145 CMa, also called Herschel 3945, is a worthwhile observation object. The astronomer John Herschel discovered him in 1837 while observing from the Cape of Good Hope . A golden yellow and a whitish shining star appear in the telescope. However, the two stars are not physical; that is, bound together by gravity , but stand in one direction when viewed from the earth. So it is an optical double star .
Variable stars
| object | Apparent brightness likes | period | Type |
|---|---|---|---|
| β | 1.95 to 2.0o | 6 hours | Beta Cephei star |
| ο 1 CMa | 3.8 to 4.0 | irregular | Slowly irregularly changing star |
| 27 CMa | 4.4 to 4.7 | irregular | Gamma Cassiopeiae star |
| ω CMa | 3.6 to 4.2 | irregular | Gamma Cassiopeiae star |
| UW CMa | 4.8 to 5.3 | 4.3934 days | Beta Lyrae Star |
| VY CMa | 6.5 to 9.6 | irregular | Slowly irregularly changing star |
β Canis Majoris ( Murzim , Arabic for "Herald"), is a pulsation-variable star of the Beta Cephei type, 715 light years away . Its brightness changes regularly in a rhythm of 6 hours.
The stars ο 1 (2000 light years), 27 (1000 light years) and ω (500 light years) change their brightness at irregular intervals, whereby the brightness fluctuations are not particularly pronounced.
UW CMa is a variable star of the Beta-Lyrae type at a distance of 5000 light years. Its brightness changes between 4.8 mag and 5.3 mag with a period of 4 days, 9 hours and 26 minutes
VY CMa is a red supergiant and one of the largest known stars by diameter.
Messier and NGC objects
| Messier (M) | NGC | other | Apparent brightness likes | Type | Surname |
|---|---|---|---|---|---|
| M 41 | 2287 | 5 | Open star cluster | ||
| 2359 | 9 | Gas mist | |||
| 2360 | 7th | Open star cluster | |||
| 2362 | 4th | Open star cluster | |||
| Collinder 140 | 5.5 | Open star cluster |
There are four open star clusters and a gas nebula in the Big Dog . The French astronomer and comet hunter Charles Messier added the star cluster M 41 to his catalog of foggy objects ( Messier catalog ).
M 41 can easily be found as it stands below the Sirius. It can be seen with the naked eye and was probably known in ancient times. The star cluster has a parallax of 1.36 mas and is therefore about 2400 light years away. In binoculars and in the small telescope it is a very beautiful sight, around 40 individual stars become visible. About 100 stars up to the 13th magnitude are visible in larger telescopes.
NGC 2359 is a gas nebula in about 4000 (?) Light years that was discovered by Wilhelm Herschel in 1785 . In the telescope it appears as a foggy spot. When using an interference filter (e.g. UHC filter) interesting structures become visible.
NGC 2360 was discovered by Karoline Herschel in 1785 . The star cluster is about 3,600 light years away. In the middle telescope it can be resolved into about 50 single stars up to the 12th magnitude.
NGC 2362 , discovered by Wilhelm Herschel in 1785, is 4400 light years away. In the binoculars it appears star-shaped. To fully resolve it, you need a larger telescope. The brightest star in the cluster is the triple star τ CMa described above. NGC 2362 is one of the youngest open star clusters we know, around a million years old.
Collinder 140 was discovered by Nicolas Lacaille in 1752 . It is about 1270 light years away. About 15 individual stars can be seen in larger binoculars.
See also
Web links
Individual evidence
- ↑ a b Gerhard Fasching: Constellation studies, sky maps, celestial bodies, constellations . Springer-Verlag, 2013, ISBN 978-3-322-86264-8 , pp. 131 ( limited preview in Google Book search).
- ^ Gerd Graßhoff: The History of Ptolemy's Star Catalog . Springer Science & Business Media, 2013, ISBN 978-1-4612-4468-4 , p. 36 ( limited preview in Google Book search).
- ↑ Milton D. Heifetz, Wil Tirion: A Walk Through the Heavens: A Guide to Stars and Constellations and Their Legends. Cambridge University Press, 2004, p. 53.
- ↑ SIMBAD
- ↑ SIMBAD
- ↑ SIMBAD
- ↑ SIMBAD