Eagle (constellation)

Observation

Location

The constellation of the Eagle belongs to the Triangle of summer.

She recognizes herself directly by the alignment of three stars whose Alpha Aquilae (Altaïr) is the center, and β and γ Aql the ends. This alignment forms the “head” of the eagle.

If the Grand square of PEGASE is visible, the constellation is in the alignment of the square towards the west.

Form

The constellation is easy to visualize, compact and rather luminous (mag 4), but its head all in length rather makes think of a Ptérodactyle that with an eagle.

The triangle whose tops are γ (top of the head), θ (end of the wing) and δ (center of the body) appreciably equilateral, and is marked by small intermediate rather brilliant star alignments. On the basis of the head of the Eagle, centered on Altaïr, one locates easily θ Aql, the extremity of the wing Is. From there, one goes up the wing towards the West by a small alignment of three stars which passes by η Aql (variable) and fall on δ Aql, in the center of the body of the Eagle. In the alignment of the “body”, one can see μ Aql between γ and δ. Into the prolongation of the “body”, one falls on λ Aql, which marks the end of the tail.

Other side, the symmetrical brilliant star of θ is ζ Aql, which marks the Northern wing. Beside it ε Aql, extremity of the wing. (These two stars are called Deneb Al Okab, which means in fact “the tail of the falcon”). The end of the wing ε ζ point towards μ, on the neck, and from there towards θ Aql.

Close constellations

The rather brilliant star that one can see in the prolongation of the wing θ-ν-δ after 10° is the end of the tail of the Serpent, θ Ser.

The other wing points after 5° on the end of the foot of Hercules.

Opposite the head of the eagle, in the North-East one can see the form very characteristic of the Dauphin, small group rather tight. In the north of the head, one recognizes the Flèche.

In the prolongation of the two brought closer stars which form the tail of the Eagle, and with the west of this tail, one finds the Écu of Sobieski, a small not very spectacular constellation.

Alignments

Altaïr is on the alignment which leaves the Grande Ourse, according to the diagonal SOUNDS “pan”. This alignment passes by the heart of the Dragon and by its head, to come to touch Véga Lyre, then Altaïr. Alignment Véga - Altaïr makes it possible to locate 20° more with the south α Capricorne and the two “feet” of the Capricorn 15° further; and for the observers located sufficiently at the south, this alignment is prolonged to Al ir Na' (α Gruis), with an about sixty degrees Altaïr.

In the axis of the “body” of the eagle, one falls on the tail from the Scorpion, to forty degrees towards the south. It is hardly visible for the observers with the top of 40°N.

Celestial objects

See also: List of celestial objects of the Eagle

NGC 6709 : open Cluster magnitude 6,7
NGC 6755: open cluster magnitude 7,5
NGC 6760: globular Cluster magnitude 9,1
NGC 6781: Nebulous planet gear, of very round, distant form of 2 600 al
NGC 6803: planetary, distant nebula of 5 200 al

Two Nova E major were observed in the Eagle; the first in 389 av. J. - C., described like more brilliant than Venus, the second, V603 Aquilae, was briefly more brilliant than Altaïr in 1918.

Principal stars

α Aquilae (Altair)

α Aquilae (Altair), whose Arab name Al-nars Al-taïr means “the Eagle in flight”, account among the the most brilliant stars of the night sky (12th, more precisely). It is the center of an almost perfect alignment of three stars, the Wings of the Eagle , sometimes confused by error with the belt of Orion. The two other stars of this line are Alshain and Tarazed (β and γ Aql). Altair is also one of the tops of the known Astérisme under the name of the Triangle of summer, with α Lyrae (Vega) and α Cygni (Deneb).

Altaïr, a star of the principal sequence, rotates quickly in 6,5 hours. Its number of revolutions is so large (it reaches at the equator 210 km/s, that is to say more than 200 times that of the Sun) that its form is that of a clearly flattened Ellipsoïde.

Altaïr is a star doubles.

β Aquilae (Alshain)

β Aquilae (Alshain) is not the 2 E the most brilliant star of the constellation, as its place in the Désignation from Bayer could let it think, but the 8 E . It owes its β with its alignment with Alpha Aquilae/Altaïr and Gamma Aquilae/Tarazed.

Like Altaïr, it is about a double system. His/her companion is a Naine red.

γ Aquilae (Tarazed)

γ Aquilae (Tarazed or Reda) is a star from which the usual name tradionnel does not come from Arabic. Tarazed comes from the Perse which means the beam of the balance and indicated in the beginning the star Alpha Aquilae/Altaïr.

γ Aquilae is a giant star, 2960 times more brilliant than the Sun and 110 times broader. It is a star doubles whose companion is of magnitude +10,7.

ε and ζ Aql (Deneb Al Okab)

Deneb Al Okab, the Tail of the Eagle in Arabic, corresponds to the two stars ε Aql (Deneb Al Okab Borealis) and |ζ Aquilae (Deneb Al Okab Australis).

Other stars

η Aql is one of most brilliant the Céphéide S of the sky, a supergéante which can reach the brightness of its neighbor β Aql. Its luminosity varies gradually on a 7,177 days cycle.

V Aql, a little in the south of λ Aql, is one of the reddest stars of the sky (temperature of surface: 2 115 K).

History

The constellation of the Eagle was probably identified with a bird as of the XII {{exp|E}} century before the Christian era. For the Greeks, it represented the eagle of Zeus. It was mentioned by the Greek astronomers Eudoxe de Cnide () and Aratos de Soles ().

The Constellation of the Eagle, with its characteristic, visible asterisms since the latitudes of the Mediterranean basin, heard well indexed by Ptolémée in its Almageste , but under the denomination “Antinoüs and its eagle”, Antinoos being a Greek slave who became the favorite of the emperor Hadrian. Antinoüs was integrated definitively into the Eagle by Johann Bode.

Mythology

In the Hindu mythology, the three most obvious stars of the constellation, forming the head of the animal, Alpha Aquilae ir /Alta, Beta Aquilae /Alshain and Gamma Aquilae /Tarazed represented the print of the foot of Vishnou.

In European antiquity , the stars of the southern part of the Eagle were named “Ganymède”, of the name of the wine waiter of the Greek gods which would have been removed, precisely, by the eagle of Zeus.

In the Chinese history of IQ Qiao Jie, Niu Lang (Altaïr) and his/her two children (Alshain and Tarazed) are separated from their mother Zhi Nu (Véga) who is located on the other side of the Milky Way (see also Chinese Astrologie - Legend of Altaïr and Véga).

See too

Internal bonds

Constellation
List of stars of the Eagle
List of celestial objects of the Eagle

External bonds

'' Aquila '' ( The Deep Photographic Guides to the Constellations )

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