Sagittarius (constellation)
Sagittarius constellation |
|
---|---|
Latin name | Sagittarius |
Latin genitive | Sagittarii |
Abbreviation | Sgr |
Right ascension | 17 h 43 m 12 s to 20 h 28 m 41 s |
declination | −45 ° 16 ′ 39 ″ to −11 ° 40 ′ 34 ″ |
surface | 867,432 deg² rank 15 |
Completely visible | 45 ° N to 90 ° S |
Observation time for Central Europe | summer |
Number of stars brighter than 3 mag | 7th |
Brightest star (size) | Epsilon Sagittarii (1.79) |
Meteor streams | |
Neighboring constellations ( clockwise from north ) |
|
swell | IAU , |
The shooter with arrow and bow in the hand (similar to the view of Centaurus from the Uranographie of Johann Elert Bode ) |
The Sagittarius ( Latin / technical language Sagittarius , astronomical sign ♐) is a constellation of the ecliptic .
description
Sagittarius is the southernmost zodiac constellation , it lies between Scorpio and Capricorn (Capricorn).
The brightest stars of Sagittarius form a shape reminiscent of a tea kettle. In the English-speaking world, it is therefore often referred to as "Teapot".
Sagittarius lies in the star-rich areas of the Milky Way ; in this direction is the galactic center . Therefore, in Sagittarius you can find a multitude of nebulous objects, such as open star clusters , globular star clusters and gas nebulae . Even in the prism binoculars , the shooter is a magnificent sight. However, it is not easy to observe from Germany, as it is low in the sky in summer due to its southern location.
The ecliptic runs through Sagittarius, so the sun , moon and planets move through this constellation. The sun is currently in Sagittarius from December 18 to January 20.
history
The origin of the name of the constellation probably goes back to an early people of horsemen nomads and was adopted by the Sumerians .
With the Babylonians , the stars embodied Pabilsang , a god with a lion's head and wings.
For the ancient Egyptians and Indians , the constellation represented a rider or archer.
Different interpretations existed among the ancient Greeks. So you saw another centaur in the sky or Krotos , a person who invented the art of archery.
The constellation gave its name and determined the original position of the zodiac sign Sagittarius . Due to the precession movement of the earth's axis, however, the time of the passage of the sun has shifted compared to antiquity .
Sagittarius is one of the classic 48 constellations described by Ptolemy .
In 1932 Karl Jansky discovered the powerful radio source Sagittarius A * in the Schützen . According to the current state of research, it is a supermassive black hole with approx. 4.3 million solar masses in the center of the Milky Way.
On August 15, 1977 , the so-called wow signal was presumably received by the constellation Sagittarius for 72 seconds. However, the nature of the signal remains unexplained.
mythology
Sagittarius is a difficult constellation to interpret. The centaur Cheiron is often assigned to the constellation . Not only because he was a good archer, but also because he shot an arrow at the Scorpio , which stabbed the hunter Orion and this is easily recognizable when you see the constellations Scorpio and Sagittarius side by side. This is very unlikely, however, since Cheiron can already be seen in the sky as a centaur .
The legend about the satyr Krotos , son of Pan and Eupheme , the wet nurse of the Muses , may also have been assigned later.
In addition, there is no specific indication in Greek mythology as to whether this centaur represents a special character. It could just be a normal offshoot of the centaur race. This is possible because the Greeks adopted the constellation from the Babylonians . For the Babylonians, the constellation could represent a form of their main god Marduk .
Celestial objects
Stars
B. | F. | Names or other designations | Size (mag) | Lj | Spectral class |
---|---|---|---|---|---|
ε | 20th | Kaus Australis | 1.9 | 143 | B9.5 III |
σ | Nunki | 2.05 | 224 | B2.5 V | |
ζ | 38 | Askella | 2.60 | 89 | A3 IV |
δ | 19th | Kaus Medius | 2.72 | approx. 350 | K3 III |
λ | 22nd | Kaus Borealis | 2.82 | 78 | K0 IV |
π | 41 | Albaldah | 2.88 | 440 | F2 II / III |
γ | 10 | Alnasl or Nash | 2.98 | 96 | K0 III |
η | 3.10 | 149 | M2 III | ||
φ | 27 | 3.17 | 231 | B8.5 III | |
τ | 40 | 3.31 | 120 | K1 / K2III | |
ξ 2 | 37 | 3.52 | 372 | G8 / K0II / III | |
ο | 39 | Manubrij | 3.76 | 139 | K0 III |
μ | 13 | Polis | 3.84 | 3912 | B2 III |
ρ 1 | 44 | 3.92 | 122 | F0 III / IV | |
β 1 | Arkab Prior | 3.96 | 378 | B9 V | |
α | Rukbat | 3.97 | 170 | B8 V | |
ι | 4.12 | 189 | K0 III | ||
β 2 | Arkab Posterior | 4.27 | 139 | F2 III | |
θ 1 | 4.37 | 618 | B2.5 IV | ||
V3872 | 4.43 | 448 | M4 III | ||
υ | 46 | 4.52 | 1673 | F2p | |
3 | X | 4.53 | 1077 | F7 II | |
b 1 | 59 | 4.54 | 1208 | K3 III | |
HR 6766 | 4.55 | 348 | K0 III Cnpvar | ||
h 2 | 52 | 4.59 | 189 | B8 / B9V | |
HR 6842 | 4.66 | 700 | K3 III | ||
γ 1 | 4.66 | 2078 | G0 Ib / II | ||
ω | 58 | Omega Sagittarii | 4.7 | approx. 85 | G5 IV |
4th | 4.74 | 437 | B9 V | ||
HR 7652 | 4.77 | 405 | K4 III | ||
21st | 4.81 | 597 | A1 / A2V | ||
60 | 4.84 | 341 | G8 II / III | ||
ν 1 | 32 | Ain al Rami | 4.86 | 1853 | K1 II |
ψ | 4.86 | 330 | K0 / K1III | ||
HR 7029 | 4.86 | 451 | B2 V | ||
f | 56 | 4.87 | 205 | K0 III | |
d | 43 | 4.88 | 536 | K0 III | |
11 | 4.96 | 244 | K0III | ||
HR 7659 | 4.99 | 325 | K1 III / IV | ||
ν 2 | 35 | 5.00 | 270 | K1 Ib / II | |
HR 6693 | 5.00 | 935 | K5 / M0III | ||
61 | 5.01 | 292 | A2 V | ||
χ 1 | 47 | 5.02 | 221 | A4 IV / V | |
ξ 1 | 36 | 5.02 | 5018 | B9.5 Ib | |
e 2 | 55 | 5.06 | 175 | F3 IV / V | |
HR 6944 | 5.12 | 213 | B9 / B9.5 V | ||
29 | 5.22 | 750 | K2 III | ||
HR 6960 | 5.28 | 2234 | B2 III / IV | ||
15th | 5.29 | B0 / 1Ia / ab | |||
θ 2 | 5.30 | 157 | A4 / A5IV | ||
HR 7703 | 5.32 | 20th | K2 V | ||
V3961 | 5.32 | 339 | A0p | ||
V4050 | 5.33 | 619 | B7 Ib / II | ||
7th | 5.37 | 1106 | F2 / F3 II / III | ||
HR 6936 | 5.37 | 350 | A5 V | ||
28 | 5.37 | 1279 | K5 III | ||
χ 3 | 5.45 | 506 | K3 III | ||
HR 7454 | 5.46 | 101 | F7 V | ||
HR 7398 | 5.46 | 254 | K1 / K2 III | ||
14th | 5.49 | 506 | K2 III | ||
24 | 5.49 | 3434 | K3 III | ||
HR 7496 | 5.49 | 120 | F5 V | ||
HR 7211 | 5.49 | 546 | A0 V |
The brightest star in Sagittarius is Epsilon Sagittarii , a blue giant 145 light-years away with 250 times the luminosity of our sun. In the prism binoculars it appears as a double star . A 7th magnitude star becomes visible at a distance of 3.3 arc minutes . However, it is not a star system in which the stars are bound to one another by gravity . Both stars are only in the same direction when viewed from Earth. The name Kaus Australis is a combination of Latin and Arabic and means "southern arc".
Sigma Sagittarii , also a blue giant, is 245 light years away. The name Nunki goes back to the Sumerian god Ninki .
Zeta Sagittarii is a white shining star of spectral class A3, 89 light-years away . The name Askella means "armpit" (the archer).
The orange glowing Gamma Sagittarii is 96 light years away and belongs to the spectral class K0 III. The name Alnasl is of Arabic origin and is derived from "arrowhead".
Alpha Sagittarii is not, as is usually the case, the brightest star in the constellation, but only a third magnitude star. It is 170 light years away. His name Rukbat also comes from Arabic and denotes the "knee" of the archer .
Double stars
system | Vmag | distance |
---|---|---|
μ | ||
υ |
Variable stars
star | size | period | Type |
---|---|---|---|
R. | 6.7 to 12.8 | 268.8 days | Mira type |
W. | 4.3 to 5.1 | 7.595 days | Cepheid |
X | 4.3 to 4.9 | 7.011 | Cepheid |
RY | 6.0 to 15 | R Coronae Borealis Star | |
RR | 6 to 14 | 334.6 | Mira |
RU | 6 to 14 | 240.3 | Mira |
W and X Sagittarii are variable stars of the Cepheid type . These stars pulsate regularly and change their brightness in the process.
RR and RU Sagittarii are variables of the Mira type . Stars of this type show strong fluctuations in brightness over long periods of time.
Messier and NGC objects
Messier (M) | NGC | other | Vmag | Type | Surname |
---|---|---|---|---|---|
M 8 | 6253 | Lagoon fog | 5.8 | Gas mist | Lagoon fog |
M 17 | 6618 | 7.0 | Gas mist | Omega nebula, swan nebula | |
M 18 | 6613 | 6.9 | Open star cluster | ||
M 20 | 6514 | 8.5 | Gas mist | Trifid Nebula | |
M 21 | 6531 | 5.9 | Open star cluster | ||
6537 | 13 | Planetary nebula | |||
M 22 | 6656 | 5.1 | Globular clusters | ||
M 23 | 6949 | 5.5 | Open star cluster | ||
M 24 | 4.6 | Cluster of stars | |||
M 25 | IC 4725 | 4.6 | Open star cluster | ||
M 28 | 6626 | 5.1 | Globular clusters | ||
M 54 | 6715 | 7.6 | Globular clusters | ||
M 55 | 6809 | 6.4 | Globular clusters | ||
M 69 | 6637 | 7.6 | Globular clusters | ||
M 70 | 6681 | 8.0 | Globular clusters | ||
M 75 | 6864 | 8.5 | Globular clusters | ||
6637 | 7.6 | Globular clusters | |||
6522 | 8.6 | Open star cluster | |||
6544 | 8.3 | Globular clusters | |||
6546 | 8.0 | Open star cluster | |||
6553 | 8.3 | Globular clusters | |||
6568 | 8.6 | Open star cluster | |||
6595 | 7.0 | Open star cluster | |||
6645 | 8.5 | Open star cluster | |||
6649 | 8.9 | Open star cluster | |||
6652 | 8.9 | Open star cluster | |||
6716 | 7.5 | Open star cluster | |||
6723 | 7.3 | Globular clusters | |||
6818 | 10.0 | Planetary nebula | |||
6822 | 8.8 | Galaxy | Barnard's Galaxy |
A variety of foggy objects are visible in Sagittarius. The French astronomer and comet hunter Charles Messier included fifteen in his catalog ( Messier catalog ). The Sagittarius is thus the constellation with the most "Messier objects".
However, the stars, gas and dark clouds of the Milky Way block the view of more distant objects. Therefore, only a brighter galaxy is visible in Sagittarius .
M 8 is an extensive gas nebula 6,000 light years away. An elongated dark cloud , reminiscent of a dark lagoon , protrudes into the bright emission nebula . M 8 is therefore also known as the “Lagoon Nebula”. An open star cluster is embedded in the nebula . The region around M 8 is an area of active star formation. Even in smaller telescopes it is a great sight.
M 17 is an emission nebula 6,000 light years away. Even in the binoculars you can see an elongated fog. Interesting structures become visible in the telescope, especially when using an interference filter. Due to its curved shape, M 17 is also known as the Omega Nebula or Swan Nebula.
M 18 is a rather inconspicuous star cluster 4,000 light years away.
M 20 is the famous, often depicted “three-part” trifid nebula, an emission nebula 6,000 light years away. Dark bands of dust run through the fog, dividing it figuratively. However, you need good observation conditions (a dark sky without artificial lighting and haze) to see the structures.
M 21 is again a rather unspectacular open star cluster at a distance of 4,000 light years.
M 22 is a globular cluster 10,000 light years away . It is the brightest globular cluster in the northern sky and can be resolved into single stars with the telescope at the edge.
M 23 is an open star cluster 2,200 light years away. About 40 stars can be seen even with smaller telescopes.
M 24 is a dense cluster of stars in the Milky Way. With the naked eye, they appear as a "star cloud".
M 25 is an open star cluster 2,500 light years away. It can already be seen with the naked eye. About 50 stars can be seen in a smaller telescope.
M 28 is a globular cluster 20,000 light years away . In the middle telescope, the edge can be resolved into single stars.
M 54 is a globular cluster which , at 80,000 light years, is very far from the sun . Nor does it belong to the globular cluster system of our Milky Way, but to a dwarf galaxy. To resolve it into single stars you need a larger telescope.
M 55 is much closer at 18,000 light years away. The globular cluster can be completely resolved into single stars in the middle telescope.
M 69 is a globular cluster 30,000 light years away. A larger telescope is required to resolve it.
M 69 , M 70 and M 75 are globular clusters that are more difficult to observe because you need a larger telescope to resolve them. M 69 and M 70 are 30,000 light years away, M 75 60,000 light years.
NGC 6818 is a planetary nebula 6,000 light years away , i.e. the ejected gas envelope of a star. An oval greenish disc is visible in the middle telescope.
NGC 6822 is a dwarf galaxy 2 million light-years away belonging to the local group . Due to its low brightness, it is relatively difficult to observe. It was only discovered by Edward Barnard in 1884 .
See also
Web links
Individual evidence
- ↑ Wissenschaft.de: A monster in its sights ( memento from July 29, 2009 in the Internet Archive ), astronomers measure the black hole in the center of the Milky Way , news from December 10, 2008
- ↑ Werner Perrey: Constellations and their legends . Urachhaus, Stuttgart 1999, ISBN 3-8251-7172-8 .