The first thing that attracts us to the night sky is, of course, the constellations. Photos and their names seem more appropriate to each other than real celestial drawings and their designations, since the image, as a rule, is equipped with auxiliary lines and is devoid of objects "interfering" with the perception of the image. However, all the beauty of the constellations can be understood only by looking for them above the head.
For the convenience of determining the position of the stars, the earth's sky is divided by the equator into the northern and southern hemispheres. The equatorial constellations are located directly on this dividing line. Their list includes, among other things, the heavenly image of Eagle, the mythical servant of Zeus.
Location
The constellation, located close to the celestial equator, is available for observation almost anywhere in the world. The best time to search for it in the northern hemisphere is from July to August. The constellation Eagle includes about a hundred stars, visible from the Earth to the naked eye. Some of them are located on the eastern branch of the Milky Way.
The brightest star of the constellation Eagle - Altair - is included in the asterism Summer Triangle. Its other two peaks are Deneb, belonging to the celestial image of Swan, and Vega, alpha Lyra, the second brightest star in the northern hemisphere. Such a neighborhood facilitates the search in the sky for both Altair itself and the whole of Oryol.
Myth
Legends and myths about the constellations always tell us why a particular pattern caught fire in the sky, and also interpret the meaning of its name. The eagle is a magnificent bird, but the strength, pride and wingspan are not enough to shine over the heads of living after death.
According to legend, the Eagle, illuminating the night sky, once served Zeus, the formidable god of the ancient Greeks. He was honored to wear thunderbolts and serve them if necessary. Zeus trusted his Eagle with important assignments. From time to time he delivered to the god the person he needed, as in the myth of Ganymede. Often the Eagle was the weapon of Zeus, his punishment for the guilty. The legend of Prometheus, perhaps, is ahead of fame for all other legends and myths about the constellations. The eagle was the same bird that every day tormented the titan, who gave people fire. The suffering of Prometheus continued until Heracles, who killed the bird, saved him. For faithful service, the saddened Zeus placed the Eagle in the sky.
Alpha
The most notable star in the constellation Eagle is Altair. By the name you can judge which heavenly drawing it refers to. Altair translated from Arabic means "flying eagle." By brightness, among all luminaries it takes the twelfth place. This alpha Eagle owes not only its size and brilliance, but also the relatively small distance that separates it from the sun. According to scientists, it is 16.8 light years. Of all the objects of spectral class A, only Sirius is closer to us.
Altair is a white star of the main sequence, superior to the Sun in mass a little less than twice. Moreover, its luminosity is 11 times greater than the corresponding parameter of the central space object of our system. As observations have shown, the brightness of Altair changes slightly, by hundredths of a magnitude. Today, in this regard, it is referred to as the Shield delta type variables.
Not quite a ball
A feature of Altair is its shape. It is far from an ideal ball: the diameter of the Alpha Eagle in the region of the equator is slightly larger than in the plane of the poles. This inequality is created due to the high speed with which Altair rotates around its axis. In the equator, it reaches 286 km / s. One such turn takes less than 9 hours. Under the influence of centrifugal forces, the star was deformed. As a result, its poles are closer to the core than the equator line, and they become more heated because of this.
Eagle family
Altair, along with the beta and the gamut of this constellation are located almost on one straight line. They and several other less visible luminaries are attributed to the asterism of the Eagle Family. Three bright points of the constellation are also combined under another name - the balance beam of Libra. True, this asterism has nothing to do with the zodiac heavenly pattern, which protects people born in September. Thanks to him, the constellation Eagle is quite simple to find.
Triple system
Beta Orla, Alshain (translated from Arabic as “hunting falcon”), is 44.7 light-years distant from the Sun and is a system of three stars. The first component is an orange subgiant with a magnitude of 3.17. Now this star is at the stage of transformation into a red giant. By mass, it exceeds our luminary by 1.3 times.
Beta Eagle B is an Alshain companion, a red dwarf with a visible brilliance of 11.4. It is significantly inferior in size to the first component: its mass is 0.3 of the corresponding parameter of the Sun. The third star, beta Eagle S, is characterized by a visible sheen of +10.5.
Orange giant
Another star in the constellation Eagle, related to the asterism of the Libra of the Libra, is Tarazet (gamma). She ranks second in brightness among all the luminaries of this heavenly pattern. At the same time, the distance from the Sun to the gamut of the Eagle significantly exceeds this indicator for Altair and Alshain. It is estimated at 460 light years. If not for this value, then Tarazet would have outstripped the alpha of the Eagle, since its brightness above the sun is more than 2.5 thousand times. The apparent magnitude of the object is 2.72.
The size of the star is quite impressive: the diameter of Tarazet is so huge that if you place the star in place of the sun, it will occupy the entire space up to the orbit of Venus.
Gamma Eagle is not a solitary star. Tarazet has a companion with a visible sheen of 10.7.
Variables
The constellation Eagle has several variables such as Cepheus delta, also called Cepheids. These include this Eagle, changing its luster in the range from 3.5 to 4.4m with a period of just over 7 days. It was discovered by E. Pigott a year before the well-known discovery by Goodrayk of the variability of the Cepheus delta. Three more variable stars of this celestial pattern are available for observation from the Earth with binoculars: FF, TT and U Eagle.
In common with the black hole
One of the most interesting objects of the Oryol constellation is SS433, located at a distance of 18 thousand light years from the Sun. The star is an eclipsing x-ray binary system. Presumably, one of its components is a black hole, the second is a star of spectral class A. Both revolve around a single center of mass in about thirteen days.
This system appeared as a result of the explosion of a massive luminary that happened about ten thousand years ago and caused the formation of the nebula W50. A black hole is the remains of a collapsed supernova nucleus.
The substance of the star of the system flows constantly to the black hole, forming an accretion disk around it and heating up. As a result of an increase in temperature, x-ray radiation constantly emits from the surface of the object. In different directions, jets of matter are thrown into space. They rush into space at a speed of about a quarter of the speed of light. In general, the picture of the interaction of objects in the system is similar to those illustrations, which are often accompanied in various manuals by an explanation of the processes occurring near a black hole.
New
In 1999, the constellation Eagle shone a little differently than usual. One of the luminaries increased its brilliance by 70 thousand times. Subsequently, it was called V1494. The brightness of the star increased during the period from December 1 to 4. It belongs to the so-called classic new, which is a system of two companions, one of which is a white dwarf. The substance from the second star flows to the dwarf and accumulates, sooner or later leading to an explosion. The latter is seen from Earth as a gradually increasing brilliance. According to existing data, after such a cataclysm, the system does not decay. The substance in it continues to flow from companion to companion. Centuries later, another explosion is expected.
Planetary systems
Several stars belonging to the celestial image of the Eagle possess planets. These include, for example, Xi Orla. This is an orange giant, surpassing the Sun in a number of parameters: its size is 12 times larger and its luminosity is 69 times larger. The mass is also more significant than the sun, but not on such a scale - only 2.2 times. The surface temperature of Xi Orel, on the contrary, is lower, and does not reach 5 thousand degrees.
A planet orbiting a star was discovered in 2008 by Japanese astronomers. It belongs to the class of gas giants, surpassing 2.8 times the mass of Jupiter. For one revolution around the Xi Eagle, the planet takes 136 days.
Nebula
The eagle is a constellation (photo is presented below), which has a very beautiful object on its “territory”. This is the Shining Eye Nebula or NGC 6751. A hot star in the center of a space formation resembles a pupil. The radiation and winds created by it form streams on the images of telescopes, very similar to the iridescent colors in the iris.
The shining eye is a classic planetary nebula with a diameter approximately 600 times the size of the solar system. The exact value of the parameter is estimated at 0.8 light years. The nebula separates 6.5 thousand light years from our luminary.
The starry image of the Eagle is another stretch of sky full of impressive objects. The pattern of the constellation, photos and names of individual stars hide a lot of interesting information. Thanks to the capabilities of modern equipment, everyone can see what this or that part of the celestial Eagle looks like, remote from us for many tens and hundreds of light years.
The uniqueness of the information era in which we live is that you can very quickly find all the facts associated with a particular object: legends (about the names of the constellations or their origin) belonging to different peoples and centuries, the latest data on the characteristics of stars, finally photos of telescopes. Today, raising his eyes to the night sky, you can not only enjoy what you see, but very clearly imagine how amazing beauty is hidden in its depths.