Eagle (constellation)

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Constellation
eagle
Aquila constellation map.png
Legend
Latin name Aquila
Latin genitive Aquilae
Abbreviation Aql
Right ascension 18411818 h 41 m 18 s to  20 h 38 m 44 s203844
declination 1884841−11 ° 51 ′ 59 ″ to  + 18 ° 41 ′ 18 ″2184118
surface 652,473 deg²
rank 22
Completely visible 78.6 ° N to 71.8 ° S
Observation time for Central Europe May - September
Number of stars brighter than 3 mag 3
Brightest star (size) Altair (Atair) (0.77)
Meteor streams

no

Neighboring constellations
(
clockwise from north )
swell IAU ,
From the Uranometria by Johann Bayer.
From the Uranometria by Johann Bayer .

The eagle ( Latin Aquila ) is a prominent constellation in the northern summer and autumn skies .

The constellation eagle as seen on autumn evenings in the southwest
Animation with fade-in of the constellation eagle (Aquila) with its main star Altair, the constellations dolphin (Delphinus) and arrow (Sagitta) as well as the summer milky way recorded in the star park Westhavelland in the southern starry sky.

description

The eagle, with its swan and lyre, is one of the most striking summer constellations . Due to the strikingly bright main star Altair (α Aquilae), the southern corner of the extensive summer triangle , it can easily be found in the summer and autumn skies. Above and below Altair are the bright stars Tarazed (γ Aquilae) and Alschain (β Aquilae). The three stars form the head of the eagle as it flies northeast towards the swan. The remaining stars are supposed to represent the bird's outstretched wings.

The band of the Milky Way - coming from the constellation Swan - pulls through the eagle and on to Sagittarius , where the center of our galaxy is. If you wander through the constellations with binoculars , you will see interesting structures in the Milky Way: extremely star-rich, but also dark areas, 3–4 bright gas nebulae and several star clusters .

etymology

The eagle is one of the 48 constellations of ancient Greek astronomy , which were already described by Claudius Ptolemy .

The Arabs translated his paraphrases in the 8th and 9th centuries. The name is therefore a mixture of old Arabic - mythological and Greek terms. The Latin name Aquila is a shortened form of the original Arabic term Arabic النسر الطائر, DMG an-Nasr aṭ-Ṭāʾir  'The flying eagle', where aṭ-Ṭāʾir refers to the meanings "the flying one" and "the fugitive". The Arabs differentiated the constellation from the lyre by referring to it as "The falling (or descending) eagle" (النسر الواقع / an-nasr al-wāqiʿ ) called.

The single use of the word aṭ-Ṭāʾir for “bird”, which can also be used as a synonym, includes all flight characteristics associated with it, but cannot be transferred anachronistically to the earlier name “literally”.

The astronomical name therefore has its root from the Arabic name an-Nasr ("the eagle").

history

The main star Altair (also Ataiïr) has been selected by the Sumerians and Babylonians of Eagle Star called. The southern part of the eagle was also known as the Antinous until the early 19th century . Antinous was a lover of Hadrian , whose legendary self-sacrifice in the Nile for his emperor was honored by this constellation. Antinous was equated with Ganymede . The picture below comes from Johann Elert Bode's atlas Presentation of the Stars and shows the constellation as it is described in the ancient sources.

mythology

There are several interpretations of the mythological origin of the name.

On the one hand, the eagle is said to come from the legend about Heracles . Prometheus , who had brought fire to man against the will of the gods, was chained to a rock by Zeus in the Caucasus Mountains as punishment . Every day an eagle appeared and ate from the unfortunate's liver, which grew back completely by the next day. When Heracles found Prometheus, he freed him from the chains and shot the eagle off with an arrow.

According to another interpretation, it is the eagle that carried the lightning bolts of Zeus and kidnapped the young man Ganymede (represented by the constellation Aquarius ) to Olympus to serve as cupbearer there.

According to another interpretation, the constellations of the summer triangle (eagle, falling vulture ( lyre ) and swan ) are the Stymphalic birds .

Celestial objects

Stars

See also list of stars in the constellation Eagle

Engraving of the constellation eagle
B. F. Names or other designations Size (mag) Lj Spectral class
101α 53 Altair (Atair) 0.76 16.7 A7 Vn
103γ 50 Tarazed 2.72 390 K3 II
106ζ 17th Deneb el Okab Australis 2.99 83 A0 IV-Vnn
108θ 65 Theta Aquilae 3.22 290 B9.5 III
104δ 30th Delta Aquilae 3.36 51 F0 IV + K (?)
111λ 16 Lambda Aquilae 3.43 124 B9 Vn
102β 60 Alschain 3.71 44.7 G9.5 IV + M3
107η 55 Eta Aquilae 3.80 1,400 F6 Iab + B9.8 V
105ε 13 Deneb el Okab Borealis 4.02 150 K1 III
200ii 12 4.02 144 K1 III
200ll 71 4.33 340 G7.5 III
109ι 41 Iota Aquilae 4.36 400 B5 III
112μ 38 My Aquilae 4.45 108 K3 III
114ξ 59 Xi Aquilae 4.71 180 G9.5 III
113ν 32 Ny Aquilae 4.72 3,000 F2 Ib
400 70 4.88 1,300 K4 III
400 69 4.90 200 K1-2 III
110κ 39 Kappa Aquilae 4.96 1,700 B0.5 IIIn
200ff 26th 4.99 150 G8 – K0 IV
400 4th 5.01 470 B9 V
200ee 36 5.03 530 K5 III
400 18th Y 5.09 (var) 700 B8 III
115ο 54 Omicron Aquilae 5.10 63 F8 V
400 37 5.12 460 G8.5 III
400 23 5.15 370 K1 II-III
400 21st V1288 5.15 (var) 700 B7 III
200bb 31 5.16 49.5 G7 IV
118σ 44 Sigma Aquilae 5.17 800 B3 V
400 19th 5.23 150 F0 III – IV
400 57 5.26 500 B7 Vn + B8 V
400 11 5.26 158 F8 V
121φ 61 Phi Aquilae 5.28 220 A1 IV
124ω1 25th Omega Aquilae 5.28 410 F8 V
400 HR 7794 5.30 250 G8 III – IV
122χ 47 Xi Aquilae 5.31 850 G2 Ib + B5.5
400 20th 5.34 1,000 B2-3 II
400 FF 5.38 1,300 F6 Ib
200hH 15th 5.39 290 K0-1 III
400 51 5.39 91 F5 V
200 gG 14th 5.42 500 B9 IV
200dd 27 5.45 440 B9 III
400 66 5.47 700 K4 III
119τ 63 Tau Aquilae 5.51 460 K0 III
200aA. 28 V1208 5.52 340 F0 III + G5
400 22nd 5.57 540 A1 V
400 62 serpentis 5.57 280 G9 III
400 HR 7300 5.57 700 G8 II-III
400 V1291 5.62 (var) 260 F0 VpSrCrEu
400 58 5.63 370 B9 IV
400 HR 7307 5.63 400 B9.5V
400 45 5.64 350 A2 V
400 14 Sagittae 5.66 600 B9pHgMn
400 5 5.68 350 kA3hA5VmA6 + kA4hF0VmF
400 42 5.68 105 F3 IV-V
400 62 5.68 420 K3 III
116π 52 5.74 500 G8 III + A2 V
400 HR 7389 5.75 180 F6 III
200cc 35 V1431 5.78 (var) 200 A0 IVp
120υ 49 5.91 170 A3 IV
123ψ 48 6.24 1,000 B9 III-IV

The main star of the eagle is called Altair (α Aquilae). Altair is a white main row dwarf with an apparent magnitude of 0.76 and belongs to the spectral type A7n and luminosity class V. Not only is it the brightest, but also the closest to the Sun of all the stars in the constellation Eagle, at a distance of 16.7 light years. Based on the surface temperature of 7,800 K and 1.7 times the solar diameter, its luminosity can be calculated to be 11 times the solar luminosity . Altair rotates on its own axis in just a few hours, which is why the star globe is clearly flattened.

The second brightest star in the eagle, Tarazed (γ Aquilae), is one of the bright giant stars . Accordingly, the star has expanded to about 100 times the solar diameter. Its mass is five to six times that of the sun. Tarazed has spectral class K3 and is 390 light years away from us.

Beta Aquilae (β Aquilae) is a sub-giant of spectral G9,5. The star has 1.4 times the mass and three times the diameter of the Sun and a surface temperature of 5,200 K. Together with a red dwarf, it forms a binary star system. The distance to the sun is 44.7 light years. The Arabic name "Alschain" means " peregrine falcon ".

In 1992 ρ Aquilae moved from the eagle to the neighboring constellation Dolphin due to its own movement . Conversely, 14 Sagittae and 62 Serpentis, contrary to their Flamsteed names , which refer to the constellations arrow and snake , are located in the eagle. But this is justified by compromises in the introduction of the modern constellation borders and not by the proper movement of the stars.

Exotic objects in the eagle are, for example, the yellow hypergiant IRC + 10420 , the X-ray double stars SS 433 and GRS 1915 + 105 , the double pulsar PSR 1913 + 16 and the gamma source SGR 1900 + 14 .

Double stars

system Sizes distance
β 3.7 m / 11.9 m 13.4 ″
ζ 3.0 m / 12.0 m / 11.8 m 7.2 ″ / 161.3 ″
π 6.3 m / 6.8 m 1.5 ″
χ 5.4 m / 6.6 m 0.4 ″
H 5.4 m / 6.8 m 39.7 ″
5 5.9 m / 7.5 m 12.7 ″
18th 5.4 m / 6.4 m 0.3 ″
23 5.3 m / 8.3 m 3.2 ″
28 5.5 m / 9.0 m 60.2 ″
57 5.7 m / 6.4 m 35.9 ″
Goddess 752 10.6 m / 17.3 m 75.8 ″

Alschain (β Aquilae) is orbited by a red dwarf star. This is 13.4 ″ from the main star. It can only be observed in larger amateur telescopes, as otherwise it will be outshone by the much brighter main star.

The single stars of π Aquilae are 1.5 ″ apart. Due to its almost identical apparent brightness, this double star is well suited as a test object for a small amateur telescope or telescope. A refractor with a 10 cm opening separates it with a magnification of approx. 180 times. When using a reflector, a slightly larger opening and higher magnification is recommended.

18 Aquilae (Y Aquilae) is a star system about 700 light years away with an orbital period of 205 years. 0.3 ″ apart, the components are too close together to separate in an amateur telescope. One of the two components is an eclipsing star with a period of 1.302 days. Thus 18 Aquilae is a triple system.

With a distance of 18.7 light years, Gliese 752 is a star system relatively close to the Sun. It consists of two red dwarfs that form a physical binary star. These are Gliese 752 A with 10.6 m and Gliese 752 B - better known as Van Biesbroeck 10 (VB 10) - with only 17.3 m . VB 10 belongs to the M8 spectral type and has only 0.08 solar masses. For a long time it was one of the lowest mass, coolest and faintest known stars. In 2009 the discovery of a planet around VB 10 was announced, but this was refuted the following year. Gliese 752 A and VB 10 are 75.8 ″ apart. In order to be able to see VB 10 visually, you need a large telescope with a 50 cm aperture.

Spectroscopic binary stars in the eagle are (in brackets the orbital period): δ Aquilae (3.42 years), ε Aquilae (3.48 years), θ Aquilae (17.122 days), σ Aquilae (1.95 days), φ Aquilae (3 , 32 days), f Aquilae (266.5 days), l Aquilae (205.2 days), 18 Aquilae (1.302 days) and 14 Sagittae (61.54 days). In the case of δ Aquilae, the companion can also be detected by periodic disturbances in the proper motion . Thus δ Aquilae is not only a spectroscopic but also an astrometric double star. But it cannot be separated into two single stars even with large telescopes, which is why it does not fall under the visual double stars.

Variable stars

star size period Type
α Amplitude = 0.004 m 0.063 days δ Scuti star
σ 5.2 m to 5.4 m 1.95 days β-Lyrae star
η 3.5 m to 4.3 m 7.18 days classic Cepheids
c Amplitude = 0.04 m 0.021 days δ Scuti star
7th Amplitude = 0.02 m 0.049 days δ Scuti star
8th Amplitude = 0.03 m 0.081 days δ Scuti star
10 5.8 m to 6.0 m 6.05 days α 2 -Canum Venaticorum star
18th 5.0 m to 5.1 m 1.30 days eclipsing star
21st 5.1 m to 5.2 m α 2 -Canum Venaticorum star
R. 5.3 m to 12 m 270 days Mira star
FF 5.2 m to 5.8 m 4.47 days classic Cepheids

The main star Altair is weakly variable. In 2005 it was identified as the δ Scuti star . Its apparent brightness varies with a main period of 1.54 hours and several secondary periods with an amplitude of 0.004 m .

σ Aquilae is an eclipse-variable star 800 light-years away . Every 1.95 days a weaker star passes in front of the bright main star, which leads to a slight decrease in brightness.

η Aquilae is a pulsation-variable star of the Cepheid type . Its brightness changes regularly with a period of 7 days, 4 hours and 15 minutes between 3.5 m and 4.3 m .

R Aquilae is a variable Mira- type star 700 light years away. The star changes its brightness over a period of about 270 days. The pulsation period has decreased significantly over the past hundred years. At the beginning of the 20th century it was 350 days. At its maximum, the star is 5.3 m bright and can barely be seen with the naked eye. At a minimum it only achieves a brightness of 12 m . To find it, you need a larger telescope.

Various novas also lit up in the eagle, including V606 Aquilae (in 1899), V604 Aquilae (1905), V603 Aquilae (1918), V500 Aquilae (1943) and V1494 Aquilae (1999).

Messier and NGC objects

Messier (M) NGC other size Type Surname
6709 6.7 m open star cluster
6738 8.3 m Asterism
6741 11.5 m planetary nebula
6749 12.4 m Globular clusters
6751 11.9 m planetary nebula Glowing Eye Nebula
6755 7.5 m open star cluster
6756 10.6 m open star cluster
6760 9.0 m Globular clusters
6772 12.7 m planetary nebula
6778 (= 6785) 12.3 m planetary nebula
6781 11.4 m planetary nebula
6790 10.5 m planetary nebula
6803 11.4 m planetary nebula
6804 12.0 m planetary nebula
6807 12.0 m planetary nebula
6814 11.2 m Barred spiral galaxy
6852 12.6 m planetary nebula
Barnard 142/143 Dark cloud E Nebula ("Dark Cave")
IRAS 19024 + 0044 pre-planetary nebula
W49B Supernova remnant
HVC 040-15 High speed cloud Smith cloud

NGC 6709 is an open star cluster 3,500 light years away. About 40 stars can be seen with a smaller telescope.

At 12.4 m, NGC 6749 is one of the faintest globular clusters in the NGC catalog. To see it, a telescope with an opening of at least 25 cm is required.

NGC 6751 is a planetary nebula about 6,500 light years away. Since its appearance in high-resolution photographs is reminiscent of a human iris , it is also known as the glowing eye nebula. On long-exposure photos it shows itself including the halo with a total diameter of about 40 ″. The diameter of the visually visible area is approx. 20 ″. An eight-inch monitor is required for observation . The central star, a white dwarf , has an apparent brightness of 14 m .

The globular cluster NGC 6760 is about 25,000 light years away. It can be seen as a faint nebula with instruments from 7 cm aperture. The first single stars at the edge are only visible from a 30 cm opening.

The planetary nebulae NGC 6803 and NGC 6807 are very small objects and difficult to observe with angular diameters of only 5 "and 2" respectively. In addition to precise knowledge of their position, a high magnification is required to be able to distinguish them from fixed stars.

1.5 ° northwest of γ Aquilae is Barnard 142/143 , also known colloquially as the "Dark Cave". This is an extensive cloud of dust that darkens the light from the stars behind. It can already be observed with binoculars . With a diameter of about 30 ′, it appears about the size of the full moon in the night sky . Their distance is estimated to be 2,000 light years.

See also

Web links

Commons : Aquila  - album with pictures, videos and audio files

Individual evidence

  1. ^ Meaning of the word in the Langenscheidt Universal Arabic dictionary. Berlin 1994, ISBN 3-468-18060-8 , p. 421.
  2. ^ Wiener Zeitung : Limits in the Sky ( Memento from April 19, 2005 in the Internet Archive ), March 18, 2005