Milky Way (MP) Is a huge gravitational linked system containing at least 200 billion stars, thousands of giant clouds of gas and dust, clusters and nebulae. Belongs to the class of barred spiral galaxies. The MP is compressed in the plane and in profile is similar to a "flying saucer".
The Milky Way with the Andromeda Galaxy (M31), the Triangle Galaxy (M33), and more than 40 dwarf satellite galaxies - their own and Andromeda - all together form the Local Group of Galaxies, which is part of the Local Supercluster (Virgo Supercluster).
Our Galaxy has the following structure: a core of billions of stars with a black hole in the center; a disk of stars, gas and dust 100,000 light-years in diameter and 1,000 light-years thick; in the middle of the disk, a bulge 3,000 light-years thick. years; sleeves; a spherical halo (corona) containing dwarf galaxies, globular star clusters, individual stars, groups of stars, dust and gas.
The central regions of the Galaxy are characterized by a strong concentration of stars: there are many thousands of them in each cubic parsec near the center. The distances between the stars are tens and hundreds of times less than in the vicinity of the Sun.
The galaxy rotates, but not evenly with the entire disk. With approaching the center, the angular velocity of rotation of stars around the center of the Galaxy increases.
In the galactic plane, in addition to the increased concentration of stars, there is also an increased concentration of dust and gas. Between the center of the Galaxy and the spiral arms (branches) there is a gas ring - a mixture of gas and dust that radiates strongly in the radio and infrared range. The width of this ring is about 6 thousand light years. It is located in an area between 10,000 and 16,000 light years from the center. The ring of gas contains billions of solar masses of gas and dust and is the site of active star formation.
The Galaxy has a corona that contains globular clusters and dwarf galaxies (Large and Small Magellanic Clouds and other clusters). The galactic corona also contains stars and groups of stars. Some of these groups interact with globular clusters and dwarf galaxies.
The plane of the Galaxy and the plane of the Solar system do not coincide, but are at an angle to each other, and the solar planetary system revolves around the center of the Galaxy in about 180–220 million Earth years - this is how long one galactic year lasts for us.
In the vicinity of the Sun, it is possible to track sections of two spiral arms, which are approximately 3 thousand light years distant from us. According to the constellations where these areas are observed, they were named the Sagittarius arm and the Perseus arm. The sun is located almost midway between these spiral branches. But relatively close to us (by galactic standards), in the constellation Orion, there is another, not very clearly defined arm - the Orion arm, which is considered an offshoot of one of the main spiral arms of the Galaxy.
The speed of rotation of the Sun around the center of the Galaxy almost coincides with the speed of the compaction wave that forms the spiral arm. This situation is atypical for the Galaxy as a whole: the spiral arms rotate at a constant angular velocity, like spokes in wheels, and the movement of stars occurs with a different pattern, therefore, almost the entire stellar population of the disk either gets inside the spiral arms or falls out of them. The only place where the speeds of stars and spiral arms coincide is the so-called corotation circle, and it is on this circle that the Sun is located.
For the Earth, this circumstance is extremely important, since violent processes occur in the spiral arms, generating powerful radiation that is destructive for all living things. And no atmosphere could protect against him. But our planet exists in a relatively quiet place in the Galaxy and has not been exposed to these cosmic cataclysms for hundreds of millions (or even billions) years. Perhaps that is why life on Earth was able to be born and survive.
An analysis of the rotation of the Galaxy has shown that it contains large masses of non-luminous (non-radiating) matter called "hidden mass" or "dark halo". The mass of the Galaxy, taking into account this hidden mass, is estimated at about 10 trillion solar masses. According to one hypothesis, some of the hidden mass may be contained in brown dwarfs, in gas giant planets that occupy an intermediate position between stars and planets, and in dense and cold molecular clouds, which have a low temperature and are inaccessible to conventional observations. In addition, in our and other galaxies there are many bodies the size of the planet, which are not included in any of the circumstellar systems and therefore are not visible through telescopes. Part of the hidden mass of galaxies may belong to "extinct" stars. According to another hypothesis, galactic space (vacuum) also contributes to the amount of dark matter. Latent mass is not only in our Galaxy, it is in all galaxies.
The problem of dark matter in astrophysics arose when it became clear that the rotation of galaxies (including our own Milky Way) cannot be correctly described if we take into account only the ordinary visible (luminous) matter contained in them. In this case, all the stars of the Galaxy would have to scatter and scatter in the vastness of the Universe. In order for this not to happen (and this does not happen), the presence of additional invisible matter with a large mass is necessary. The action of this invisible mass is manifested exclusively in the gravitational interaction with visible matter. At the same time, the amount of invisible matter should be approximately six times higher than the amount of visible matter (information about this was published in the scientific journal Astrophysical Journal Letters). The nature of dark matter, like dark energy, the presence of which is assumed in the observable universe, remains unclear.
The Milky Way is the galaxy that contains the Earth, the solar system and all the individual stars visible to the naked eye. Refers to barred spiral galaxies.
The Milky Way together with the Andromeda Galaxy (M31), the Triangle Galaxy (M33) and more than 40 dwarf satellite galaxies - their own and Andromeda - form the Local Group of Galaxies, which is part of the Local Supercluster (Virgo Supercluster).
Discovery history
Galileo's discovery
The Milky Way revealed its secret only in 1610. It was then that the first telescope was invented, which Galileo Galilei used. The famous scientist saw through the device that the Milky Way is a real conglomeration of stars, which, when viewed with the naked eye, merged into a continuous faintly shimmering strip. Galileo even succeeded in explaining the heterogeneity of the structure of this strip. It was caused by the presence of not only star clusters in the celestial phenomenon. There are also dark clouds. The combination of these two elements creates an amazing image of a nighttime phenomenon.
William Herschel's discovery
The study of the Milky Way continued in the 18th century. During this period, its most active researcher was William Herschel. The famous composer and musician made telescopes and studied the science of stars. The most important discovery of Herschel was the Great Plan of the Universe. This scientist observed the planets through a telescope and counted them in different parts of the sky. Studies have led to the conclusion that the Milky Way is a kind of stellar island in which our Sun is located. Herschel even drew a schematic blueprint for his discovery. In the figure, the star system was depicted as a millstone and had an elongated irregular shape. At the same time, the sun was inside this ring that surrounded our world. This is how all scientists imagined our Galaxy up to the beginning of the last century.
It was only in the 1920s that the work of Jacobus Kaptein saw the light of day, in which the Milky Way was described in most detail. At the same time, the author gave a scheme of the star island, which is as similar as possible to the one that is known to us at the present time. Today we know that the Milky Way is a Galaxy, which includes the solar system, the Earth and those individual stars that are visible to humans with the naked eye.
What shape does the Milky Way have?
When studying galaxies, Edwin Hubble classified them into different kinds elliptical and spiral. Spiral galaxies are disk-shaped with spiral arms inside. Since the Milky Way is disk-shaped along with spiral galaxies, it is logical to assume that it is probably a spiral galaxy.
In the 1930s, R.J. Trumpler realized that the estimates of the size of the Milky Way galaxy made by Capetin and others were erroneous, since the measurements were based on observations using radiation waves in the visible region of the spectrum. Trumpler concluded that a huge amount of dust in the plane of the Milky Way absorbs visible light. Therefore, distant stars and their clusters seem more ghostly than they really are. As such, astronomers had to find a way to see through the dust in order to accurately image the stars and star clusters within the Milky Way.
The first radio telescopes were invented in the 1950s. Astronomers have discovered that hydrogen atoms emit radiation in radio waves, and that such radio waves can penetrate the dust in the Milky Way. Thus, it became possible to see the spiral arms of this galaxy. For this, we used the marking of stars by analogy with the markings when measuring distances. Astronomers realized that O and B stars could serve this purpose.
Such stars have several features:
- brightness- they are very noticeable and often found in small groups or associations;
- warmly- they emit waves of different lengths (visible, infrared, radio waves);
- short life time- they live for about 100 million years. Given the speed at which stars rotate at the center of the galaxy, they do not travel far from their birthplace.
Astronomers can use radio telescopes to accurately match the positions of O and B stars, and use Doppler shifts in the radio spectrum to determine their speed. After carrying out such operations on many stars, scientists were able to release combined radio and optical maps of the spiral arms of the Milky Way. Each arm is named for a constellation that exists within it.
Astronomers believe that the movement of matter around the center of the galaxy creates density waves (regions of high and low density), just like you see when you stir the dough onto a cake with an electric mixer. It is believed that these density waves caused the spiral nature of the galaxy.
Thus, looking at the sky at different wavelengths (radio, infrared, visible, ultraviolet, X-ray) with the help of various ground-based and space telescopes, you can get different images of the Milky Way.
Doppler effect... Just as the high-pitched sound of a fire truck siren becomes lower as the vehicle moves away, the movement of stars affects the wavelengths of light that travel from them to Earth. This phenomenon is called the Doppler effect. We can measure this effect by measuring lines in the spectrum of a star and comparing them to the spectrum of a standard lamp. The degree of Doppler shift indicates how fast a star is moving relative to us. In addition, the direction of the Doppler shift can show us the direction in which the star is moving. If the spectrum of the star shifts to the blue end, then the star is moving towards us; if in the red side, it moves away.
Structure of the milky way
If we look closely at the structure of the Milky Way, we will see the following:
- Galactic disc... Most of the stars in the Milky Way are concentrated here.
The disk itself is split into the following parts:
- The kernel is the center of the disk;
- Arcs are areas around the nucleus, including the area directly above and below the plane of the disk.
- Spiral sleeves are areas that protrude outward from the center. Our solar system is located in one of the spiral arms of the Milky Way.
- Globular clusters... Several hundred of them are scattered above and below the plane of the disc.
- Halo... It is a large, dim area that surrounds the entire galaxy. The halo is composed of high-temperature gas and possibly dark matter.
The radius of the halo is much larger than the size of the disk and, according to some data, reaches several hundred thousand light years. The center of symmetry of the Milky Way's halo coincides with the center of the galactic disk. The halo consists mainly of very old, dim stars. The age of the spherical component of the Galaxy is over 12 billion years. The central, densest part of the halo within a few thousand light years from the center of the Galaxy is called bulge(translated from English "thickening"). In general, the halo rotates very slowly.
Compared to halo disk rotates noticeably faster. It looks like two plates folded by the edges. The diameter of the galactic disk is about 30 kpc (100,000 light years). It is about 1,000 light years thick. The rotation speed is not the same at different distances from the center. It rises rapidly from zero in the center to 200-240 km / s at a distance of 2 thousand light years from it. The mass of the disk is 150 billion times the mass of the Sun (1.99 * 10 30 kg). Young stars and star clusters are concentrated in the disk. There are many bright and hot stars among them. Gas in the disk of the Galaxy is unevenly distributed, forming giant clouds. The main chemical element in our Galaxy is hydrogen. It is about 1/4 helium.
One of the most interesting regions of the Galaxy is considered to be its center, or core located in the direction of the constellation Sagittarius. The visible radiation from the central regions of the Galaxy is completely hidden from us by powerful layers of absorbing matter. Therefore, they began to study it only after the creation of receivers for infrared and radio radiation, which is absorbed to a lesser extent. The central regions of the Galaxy are characterized by a strong concentration of stars: there are many thousands of them in each cubic parsec. Closer to the center, there are regions of ionized hydrogen and numerous sources of infrared radiation, indicative of star formation taking place there. In the very center of the Galaxy, it is assumed the existence of a massive compact object - a black hole with a mass of about a million solar masses.
One of the most notable formations are spiral branches (or sleeves). They gave the name to this type of object - spiral galaxies. The youngest stars, many open star clusters, and chains of dense clouds of interstellar gas, in which stars continue to form, are mainly concentrated along the arms. Unlike the halo, where any manifestations of stellar activity are extremely rare, a stormy life continues in the branches, associated with the continuous transition of matter from interstellar space to stars and back. The spiral arms of the Milky Way are largely hidden from us by absorbing matter. Their detailed study began after the advent of radio telescopes. They made it possible to study the structure of the Galaxy by observing the radio emission of interstellar hydrogen atoms concentrated along long spirals. According to modern concepts, the spiral arms are associated with compression waves propagating along the disk of the galaxy. Passing through the compression regions, the disk matter becomes denser, and the formation of stars from the gas becomes more intense. The reasons for the appearance of such a peculiar wave structure in the disks of spiral galaxies are not entirely clear. Many astrophysicists are working on this problem.
The place of the sun in the galaxy
In the vicinity of the Sun, it is possible to trace the sections of two spiral branches, which are approximately 3 thousand light years distant from us. According to the constellations where these areas are found, they are called the Sagittarius arm and the Perseus arm. The sun is almost halfway between these spiral branches. True, relatively close (by galactic standards) from us, in the constellation Orion, there is another, not so pronounced branch, which is considered an offshoot of one of the main spiral arms of the Galaxy.
The distance from the Sun to the center of the Galaxy is 23-28 thousand light years, or 7-9 thousand parsecs. This suggests that the Sun is located closer to the edge of the disk than to its center.
Together with all nearby stars, the Sun revolves around the center of the Galaxy at a speed of 220-240 km / s, making one revolution every 200 million years. This means that for the entire time of its existence, the Earth has flown around the center of the Galaxy no more than 30 times.
The speed of rotation of the Sun around the center of the Galaxy practically coincides with the speed with which the compaction wave moves in this region, forming a spiral arm. This situation is generally unusual for the Galaxy: the spiral branches rotate with a constant angular velocity, like the spokes of a wheel, and the motion of the stars, as we have seen, obeys a completely different pattern. Therefore, almost the entire stellar population of the disk either enters or exits the spiral branch. The only place where the speeds of the stars and spiral branches coincide is the so-called corotation circle, and this is where the Sun is located!
This circumstance is extremely favorable for the Earth. Indeed, violent processes take place in the spiral branches, generating powerful radiation that is destructive for all living things. And no atmosphere could protect against him. But our planet exists in a relatively quiet place in the Galaxy and has not experienced the influence of these cosmic cataclysms for hundreds of millions and billions of years. Perhaps that is why life could have originated and survived on Earth.
For a long time, the position of the Sun among the stars was considered the most commonplace. Today we know that this is not so: in a sense, it is privileged. And this must be taken into account when discussing the possibility of the existence of life in other parts of our Galaxy.
The arrangement of the stars
In the cloudless night sky, the Milky Way is visible from anywhere on our planet. However, only a part of the Galaxy is visible to the human eye, which is a system of stars located inside the Orion arm. What is the Milky Way? The definition of all its parts in space becomes most understandable if we consider the star map. In this case, it becomes clear that the Sun illuminating the Earth is located practically on the disk. This is almost the edge of the Galaxy, where the distance from the core is 26-28 thousand light years. Moving at a speed of 240 kilometers per hour, the Luminary spends 200 million years for one revolution around the core, so that during its entire existence it traveled around the disk, circling the core, only thirty times. Our planet is in the so-called corotation circle. This is a place where the rotation speeds of the arms and stars are identical. This circle is characterized by an increased level of radiation. That is why life, as scientists believe, could arise only on a planet near which there are a small number of stars. Our Earth was such a planet. It is located on the periphery of the Galaxy, in its quietest place. That is why there have been no global cataclysms on our planet for several billion years, which often occur in the Universe.
What will the death of the Milky Way look like?
The cosmic story of the death of our galaxy begins here and now. We can blindly look around, thinking that the Milky Way, Andromeda (our older sister) and a bunch of unknowns - our space neighbors - this is our home, but in reality there is much more. It's time to explore what else is around us. Go.
- Galaxy Triangle... With a mass of about 5% of the mass of the Milky Way, it is the third largest galaxy in the local group. It has a spiral structure, its own satellites and may be a satellite of the Andromeda galaxy.
- Large Magellanic Cloud... This galaxy makes up only 1% of the mass of the Milky Way, but is the fourth largest in our local group. It is very close to our Milky Way - less than 200,000 light-years away - and active star formation continues in it, as tidal interactions with our galaxy lead to the collapse of gas and create new, hot and large stars in the universe.
- Small Magellanic Cloud, NGC 3190 and NGC 6822... All of them have a mass of 0.1% to 0.6% of the Milky Way (and it is unclear which one is larger) and all three are independent galaxies. Each of them contains more than a billion solar masses of material.
- Elliptical galaxies M32 and M110. They may be "just" satellites of Andromeda, but each of them has more than a billion stars, and in mass they may even exceed numbers 5, 6 and 7.
In addition, there are at least 45 other known galaxies - smaller ones - that make up our local group. Each of them has a halo of dark matter surrounding it; each of them is gravitationally tied to the other, located at a distance of 3 million light years. Despite their size, mass and size, none of them will remain in a few billion years.
So the main thing
As time progresses, galaxies interact gravitationally. They not only pull together due to gravitational attraction, but also interact tidal. We usually talk about the tides in the context of the Moon pulling the Earth's oceans and creating the ebb and flow, and this is partly true. But from a galactic point of view, tides are less noticeable. A part of a small galaxy that is close to a large one will be attracted with a greater gravitational force, and a part that is farther away will experience less attraction. As a result, the small galaxy will stretch out and eventually burst apart under the influence of gravity.
The small galaxies that are part of our local group, including both the Magellanic Clouds and the dwarf elliptical galaxies, will be torn apart in this way, and their matter will be incorporated into the large galaxies with which they merge. “So what,” you say. After all, this is not entirely death, because large galaxies will remain alive. But even they will not exist forever in this state. In 4 billion years, the mutual gravitational pull of the Milky Way and Andromeda will drag galaxies into a gravitational dance that will lead to a great merger. Although this process will take billions of years, the spiral structure of both galaxies will be destroyed, leading to the creation of a single, giant elliptical galaxy at the core of our local group: Milkomed.
A small percentage of stars will be ejected during such a merger, but most will remain unharmed, with a large burst of star formation. Eventually, the rest of the galaxies in our local group will also be sucked in, leaving one large giant galaxy devouring the rest. This process will take place in all connected groups and clusters of galaxies throughout the Universe, while dark energy will push individual groups and clusters apart. But this cannot be called death, because the galaxy will remain. And it will be like this for a while. But the galaxy is made up of stars, dust and gas, and everything will come to an end someday.
Throughout the Universe, galactic mergers will take tens of billions of years. During the same time, dark energy will spread them throughout the Universe to a state of complete solitude and inaccessibility. And although the last galaxies outside our local group will not disappear until hundreds of billions of years have passed, the stars will live in them. The longest-lived stars in existence today will continue to burn their fuel for tens of trillions of years, and new stars will emerge from the gas, dust, and stellar corpses that inhabit every galaxy - albeit fewer and fewer.
When the last stars burn out, only their corpses will remain - white dwarfs and neutron stars. They will shine for hundreds of trillions or even quadrillions of years before they go out. When this inevitability happens, we will be left with brown dwarfs (failed stars) that accidentally merge, reignite nuclear fusion and create starlight for tens of trillions of years.
When, after tens of quadrillion years in the future, the last star goes out, there will still be some mass in the galaxy. This means that this cannot be called "true death."
All masses gravitationally interact with each other, and gravitational objects of different masses exhibit strange properties when interacting:
- Repeated "approaches" and close passes cause exchanges of speed and impulses between them.
- Low-mass objects are thrown out of the galaxy, while objects with higher mass plunge into the center, losing speed.
- For a fairly long period of time, most of the masses will be thrown away, and only a small part of the remaining masses will be rigidly attached.
At the very center of these galactic remains will be a supermassive black hole in each galaxy, and the rest of the galactic objects will revolve around an enlarged version of our own solar system. Of course, this structure will be the last, and since the black hole will be as large as possible, it will eat up everything it can reach. In the center of Mlekomeda there will be an object hundreds of millions of times more massive than our Sun.
But it will end, too?
Thanks to the Hawking radiation phenomenon, even these objects will one day decay. It will take about 10 80 - 10 100 years, depending on how massive our supermassive black hole becomes as it grows, but the end is coming. After that, the remains rotating around the galactic center will untie and leave only a halo of dark matter, which can also dissociate arbitrarily, depending on the properties of this very matter. Without any matter, there will no longer be anything that we once called the local group, the Milky Way and other names dear to the heart.
Mythology
Armenian, Arabic, Wallachian, Jewish, Persian, Turkish, Kyrgyz
According to one of the Armenian myths about the Milky Way, the god Vahagn, the ancestor of the Armenians, in a harsh winter stole straw from the ancestor of the Assyrians Barsham and disappeared into the sky. When he walked across the sky with his prey, he dropped straws on his way; from them, a light trail in the sky was formed (in Armenian "The Road of the Straw Stealer"). The myth about scattered straw is also spoken of by the Arabic, Hebrew, Persian, Turkish and Kyrgyz names (Kirg. samanchynyn zholu- the path of the straw man) of this phenomenon. The people of Wallachia believed that Venus stole this straw from St. Peter.
Buryat
According to Buryat mythology, good forces create the world, modify the universe. So, the Milky Way arose from milk that Manzan Gurme drained from her breast and threw out after Abai Geser, who deceived her. According to another version, the Milky Way is a "seam of the sky", sewn up after the stars poured out of it; on it, like on a bridge, tengri walk.
Hungarian
According to Hungarian legend, Attila will descend the Milky Way if the Szekeys are in danger; the stars are sparks from the hooves. Milky Way. accordingly, it is called the "road of warriors."
Ancient greek
Etymology of the word Galaxias (Γαλαξίας) and its connection with milk (γάλα) reveal two similar ancient Greek myths. One of the legends tells about the mother's milk of the goddess Hera, who was breastfeeding Hercules, spreading across the sky. When Hera found out that the baby she was breastfeeding was not her own child, but the illegitimate son of Zeus and an earthly woman, she pushed him away, and the spilled milk became the Milky Way. Another legend says that the spilled milk is the milk of Rhea, the wife of Kronos, and Zeus himself was the baby. Kronos devoured his children, as it was predicted to him that he would be overthrown by his own son. Rhea conceived a plan to save her sixth child, newborn Zeus. She wrapped a stone in baby clothes and slipped it to Kronos. Kronos asked her to feed her son one more time before he swallowed him. Milk spilled from Rhea's breast onto a bare stone was later called the Milky Way.
Indian
The ancient Indians considered the Milky Way to be the milk of the evening red cow passing through the sky. In the Rig Veda, the Milky Way is called the throne path of Aryaman. The Bhagavata Purana contains a version according to which the Milky Way is the belly of a celestial dolphin.
Inca
The main objects of observation in the astronomy of the Incas (which is reflected in their mythology) in the sky were the dark parts of the Milky Way - a kind of "constellation" in the terminology of the Andean cultures: Lama, Lama Cub, Shepherd, Condor, Partridge, Toad, Snake, Fox; as well as stars: Southern Cross, Pleiades, Lyra and many others.
Ket
In Ket myths, similar to Selkup, the Milky Way is described as the path of one of three mythological characters: the Son of Heaven (Esya), who went to hunt on the western side of the sky and froze there, the hero Albe, pursuing an evil goddess, or the first shaman Doha, who ascended this road. to the sun.
Chinese, Vietnamese, Korean, Japanese
In the mythologies of the synosphere, the Milky Way is called and compared with a river (in Vietnamese, Chinese, Korean and Japanese the name "Silver River" is retained. The Chinese also sometimes called the Milky Way "Yellow Road", after the color of the straw.
Indigenous peoples of North America
Hidatsa and the Eskimos call the Milky Way "Ash". Their myths tell of a girl who scattered ashes across the sky so that people could find their way home at night. The Cheyenne believed that the Milky Way was mud and silt lifted up by the belly of a turtle swimming in the sky. Eskimos from the Bering Strait - that these are the traces of the Creator Crow walking across the sky. The Cherokee believed that the Milky Way was formed when one hunter stole another's wife out of jealousy, and her dog began to eat cornmeal, left unattended, and scattered it across the sky (the same myth is found among the Khoisan population of the Kalahari). Another myth of the same people says that the Milky Way is the trail of a dog dragging something across the sky. Ktunakha called the Milky Way the "dog's tail", the black-footed ones called it the "wolf road". The Wyandot myth says that the Milky Way is a place where the souls of dead people and dogs come together and dance.
Maori
In Maori mythology, the Milky Way is considered the Tama-rereti boat. The bow of the boat is the constellation Orion and Scorpio, the anchor is the Southern Cross, Alpha Centauri and Hadar are the rope. According to legend, one day Tama-rereti was sailing in his canoe and saw that it was too late, and he was far from home. There were no stars in the sky, and, fearing that Tanifa might attack, Tama-rereti began to throw sparkling pebbles into the sky. The celestial deity Ranginui liked what he was doing, and he placed the Tama-rereti boat in the sky and turned the pebbles into stars.
Finnish, Lithuanian, Estonian, Erzyan, Kazakh
The Finnish name is Fin. Linnunrata- means "The way of the birds"; a similar etymology and the Lithuanian name. The Estonian myth also links the Milky ("bird") Way with the flight of a bird.
Erzyan name - "Kargon Ki" ("Crane Road").
The Kazakh name is “Құs zholy” (“The Way of the Birds”).
Interesting facts about the Milky Way galaxy
- The Milky Way began forming as a cluster of dense regions after the Big Bang. The first stars to appear were in globular clusters that continue to exist. These are the oldest stars in the galaxy;
- The galaxy has increased its parameters by absorbing and merging with others. Now she is taking stars from the Sagittarius Dwarf Galaxy and the Magellanic Clouds;
- The Milky Way moves through space with an acceleration of 550 km / s in relation to the relic radiation;
- Hidden in the galactic center is a supermassive black hole Sagittarius A *. The mass is 4.3 million times that of the sun;
- Gas, dust and stars revolve around the center at a speed of 220 km / s. This is a stable indicator, implying the presence of a shell of dark matter;
- A collision with the Andromeda galaxy is expected in 5 billion years.
Planet Earth, solar system, and all the stars visible to the naked eye are in Milky Way Galaxy, which is a barred spiral galaxy with two pronounced arms starting at the ends of the bar.
This was confirmed in 2005 by the Lyman Spitzer Space Telescope, which showed that the central bar of our galaxy is larger than previously thought. Spiral galaxies with a bar - spiral galaxies with a bar ("bar") of bright stars emerging from the center and crossing the galaxy in the middle.
Spiral branches in such galaxies begin at the ends of the barriers, whereas in ordinary spiral galaxies they exit directly from the core. Observations show that about two-thirds of all spiral galaxies are barred. According to existing hypotheses, the barriers are centers of star formation that support the birth of stars in their centers. It is assumed that, through orbital resonance, they let gas from the spiral arms pass through them. This mechanism provides an influx of building material for the birth of new stars. The Milky Way along with the Andromeda Galaxy (M31), the Triangle (M33), and more than 40 smaller satellite galaxies form the Local Group of Galaxies, which, in turn, is part of the Virgo Supercluster. "Using an infrared image from NASA's Spitzer telescope, scientists have discovered that the Milky Way's elegant spiral structure has only two dominant arms from the ends of the central bar of stars. Our galaxy was previously thought to have four main arms."
/s.dreamwidth.org/img/styles/nouveauoleanders/titles_background.png "target =" _blank "> http://s.dreamwidth.org/img/styles/nouveauoleanders/titles_background.png) 0% 50% no-repeat rgb (29, 41, 29); "> Galaxy structureIn appearance, the galaxy resembles a disk (since most of the stars are located in the form of a flat disk) with a diameter of about 30,000 parsecs (100,000 light years, 1 quintillion kilometers) with an estimated average thickness of the disk of about 1,000 light years, the diameter of the bulge is the center of the disk is 30,000 light years. The disk is immersed in a spherical halo, and a spherical crown is located around it. The center of the galactic nucleus is located in the constellation Sagittarius. The thickness of the galactic disk where it is solar system with planet Earth is 700 light years. The distance from the Sun to the center of the Galaxy is 8.5 kilo parsecs (2.62.1017 km, or 27,700 light years). solar system is located on the inner edge of the sleeve called the Orion sleeve. In the center of the Galaxy, apparently, there is a super massive black hole (Sagittarius A *) (about 4.3 million solar masses) around which, presumably, a black hole with an average mass of 1000 to 10,000 solar masses and an orbital period of about 100 years revolves and several thousand comparatively small ones. The galaxy contains, according to the lowest estimate, about 200 billion stars (modern estimates range from 200 to 400 billion). As of January 2009, the mass of the Galaxy is estimated at 3.1012 solar masses, or 6.1042 kg. The bulk of the Galaxy is contained not in stars and interstellar gas, but in a non-luminous halo of dark matter.
Compared to the halo, the galactic disk rotates noticeably faster. Its rotation speed is not the same at different distances from the center. It rapidly increases from zero in the center to 200-240 km / s at a distance of 2 thousand light years from it, then decreases slightly, increases again to approximately the same value, and then remains almost constant. The study of the features of the rotation of the disk of the Galaxy made it possible to estimate its mass; it turned out that it is 150 billion times greater than the mass of the Sun. Age Milky Way Galaxy is equal to13,200 million years old, almost as old as the universe. The Milky Way is part of the Local Group of Galaxies.
/s.dreamwidth.org/img/styles/nouveauoleanders/titles_background.png "target =" _blank "> http://s.dreamwidth.org/img/styles/nouveauoleanders/titles_background.png) 0% 50% no-repeat rgb (29, 41, 29); "> Location of the Solar System solar system is located on the inner edge of an arm called the Orion arm, in the marginal part of the Local Supercluster, which is sometimes also called the Virgo Super Cluster. The thickness of the galactic disk (where it is solar system with the planet Earth), is 700 light years. The distance from the Sun to the center of the Galaxy is 8.5 kilo parsecs (2.62.1017 km, or 27,700 light years). The sun is closer to the edge of the disk than to its center.
Together with other stars, the Sun revolves around the center of the Galaxy at a speed of 220-240 km / s, making one revolution in about 225-250 million years (which is one galactic year). Thus, for the entire time of its existence, the Earth has flown around the center of the Galaxy no more than 30 times. The galactic year of the Galaxy is 50 million years, the orbital period of the bar is 15-18 million years. In the vicinity of the Sun, it is possible to track sections of two spiral arms, which are approximately 3 thousand light years distant from us. According to the constellations where these areas are observed, they were named the Sagittarius arm and the Perseus arm. The sun is located almost midway between these spiral branches. But relatively close to us (by galactic standards), in the constellation Orion, there is another, not very clearly defined arm - the Orion arm, which is considered an offshoot of one of the main spiral arms of the Galaxy. The speed of rotation of the Sun around the center of the Galaxy almost coincides with the speed of the compaction wave that forms the spiral arm. This situation is atypical for the Galaxy as a whole: the spiral arms rotate at a constant angular velocity, like spokes in wheels, and the movement of stars occurs with a different pattern, therefore, almost the entire stellar population of the disk either gets inside the spiral arms or falls out of them. The only place where the speeds of the stars and spiral arms coincide is the so-called corotation circle, and it is on this circle that the Sun is located. For the Earth, this circumstance is extremely important, since violent processes occur in the spiral arms, generating powerful radiation that is destructive for all living things. And no atmosphere could protect against him. But our planet exists in a relatively quiet place in the Galaxy and has not been exposed to these cosmic cataclysms for hundreds of millions (or even billions) years. Perhaps this is why life on Earth was able to be born and survive, the age of which is 4.6 billion years. Diagram of the location of the Earth in the universe in a series of eight maps, which show, from left to right, starting with the Earth, moving in Solar system, to neighboring star systems, to the Milky Way, to local Galactic groups, tolocal Virgo superclusters, on our local super-cluster, and ends up in the observable universe.
Solar system: 0.001 light years
Neighbors in interstellar space
Milky Way: 100,000 light years
Local Galactic Groups
Local Super Cluster Virgo
Local over the galaxy cluster
Observable universe
The Milky Way is a striped spiral galaxy. Our galaxy is between 100,000 and 180,000 light years across in diameter. It is estimated by scientists to contain 100-400 billion stars. There are probably at least 100 billion planets in the Milky Way. The solar system lies within the disk, 26,490 light-years from the Galactic Center, at the inner edge of the Orion Arm, one of the spiral concentrations of gas and dust. Stars in the innermost 10,000 light years form a bulge and one or more rods. The galactic center is an intense radio source known as Sagittarius A, which is probably 4.100 million solar masses.
Speed and radiation
Stars and gases move at a speed of about 220 kilometers per second over a wide range of distances from the orbit of the Galactic Center. Constant rotational speed contradicts the laws of Keplerian dynamics and assumes that most of the mass of the Milky Way does not emit or absorb electromagnetic radiation. This mass was called "dark matter". The rotation period is about 240 million years at the position of the Sun. The Milky Way moves at a speed of about 600 km per second relative to extragalactic frames of reference. The oldest stars in the Milky Way are nearly as old as the universe itself, and likely formed soon after the Dark Ages of the Big Bang.
Appearance
The center of the Milky Way is visible from Earth as a hazy streak white light, about 30 ° wide, curved by the night sky. All of the individual stars in the night sky visible to the naked eye are part of the Milky Way. The light comes from an accumulation of unresolved stars and other material located in the direction of the galactic plane. Dark areas within the strip, such as the Great Rift and Koalsak, are areas where interstellar dust blocks light from distant stars. The region of the sky that the Milky Way hides is called the Avoidance Zone.
Brightness
The Milky Way has a relatively low surface brightness. Its visibility can be greatly reduced by background such as light or moonlight. For the Milky Way to be visible, the sky must be darker than normal. It should be visible if the limit is approximately + 5.1 or higher and shows more detail at + 6.1. This makes the Milky Way difficult to access from brightly lit urban or suburban areas, but highly visible from rural areas when the Moon is below the horizon. The New World Atlas of Artificial Brightness of the Night Sky shows that more than one third of the world's population cannot see the Milky Way from their homes due to air pollution.
The size of the Milky Way galaxy
The Milky Way is the second largest galaxy in the local group, with its stellar disk about 100,000 litas (30 kpc) in diameter and an average thickness of about 1,000 litas (0.3 kpc). The ring-shaped string of stars wrapped around the Milky Way may belong to the galaxy itself, hovering higher and lower relative to the galactic plane. If so, it will speak of a diameter of 150,000-180,000 light years (46-55 kpc).
Weight
Estimates of the mass of the Milky Way vary depending on the method and data used. At the lower end of the estimate range, the mass of the Milky Way is 5.8 × 1011 solar masses (M☉), which is slightly less than the mass of the Andromeda galaxy. Measurements using a very long baseline array in 2009 showed speeds as high as 254 km / s (570,000 mph) for stars on the outer edge of the Milky Way. Since the orbital velocity depends on the total mass in the orbital radius, this suggests that the Milky Way is more massive, roughly equal to the mass of the Andromeda Galaxy at 7 × 1011 M☉ within 160,000 liters (49 kpc) of its center. In 2010, a measurement of the radial velocity of halo stars showed that the mass contained within 80 kiloparsecs is 7 × 1011 M☉. According to a study published in 2014, the mass of the entire Milky Way is estimated at 8.5 × 1011 M☉, which is about half the mass of the Andromeda Galaxy.
Dark matter
Much of the Milky Way is dark matter, an unknown and invisible form that gravitationally interacts with ordinary matter. The dark matter halo is distributed relatively evenly over a distance of more than one hundred kilometers (kpc) from the Galactic Center. Mathematical models of the Milky Way assume that the mass of dark matter is 1-1.5 × 1012 M☉. Recent studies show a range in mass of 4.5 × 1012 M☉ as well as a dimension of 8 × 1011 M☉.
Interstellar gas
The total mass of all stars in the Milky Way is estimated to be between 4.6 × 1010 M☉ and 6.43 × 1010 M☉. In addition to stars, there is also interstellar gas containing 90% hydrogen and 10% helium, with two-thirds of the hydrogen in atomic form and the remaining third in molecular hydrogen. The mass of this gas is equal to 10% or 15% of the total mass of the stars in the galaxy. Interstellar dust accounts for another 1% of the total mass.
The structure and size of our galaxy
The Milky Way contains 200 to 400 billion stars and at least 100 billion planets. The exact figure depends on the number of very low mass stars that are difficult to detect, especially at distances of more than 300 litas from the Sun. For comparison, the neighboring one contains approximately three trillion stars, and therefore exceeds the size of our galaxy. The Milky Way may also contain perhaps ten billion white dwarfs, billions of neutron stars and one hundred million black holes. Filling the space between stars is a disk of gas and dust called the interstellar medium. This disk has at least a comparative radial extent to the stars, while the thickness of the gas layer ranges from hundreds of light years for colder gas to thousands of light years for warmer gas.
The Milky Way consists of a rod-shaped core region surrounded by a disk of gas, dust and stars. The distribution of masses in the Milky Way is very similar to the Sbc type in the Hubble classification, representing spiral galaxies with relatively free arms. Astronomers first began to suspect that the Milky Way was a closed spiral galaxy, rather than an ordinary spiral galaxy, in the 1960s. Their suspicions were confirmed by observations by the Spitzer Space Telescope in 2005, in which the Milky Way's central barrier was larger than previously thought.
Ideas about the size of our galaxy can vary. The disk of stars in the Milky Way does not have a sharp edge, beyond which there are no stars. Rather, the concentration of stars decreases with distance from the center of the Milky Way. For reasons that are not understood, beyond a radius of about 40,000 litas from the center, the number of stars per cubic parsec falls much faster. The surrounding galactic disk is a spherical galactic halo of stars and globular clusters that extends further outward, but is limited in size by the orbits of two satellites of the Milky Way - the Large and Small Magellanic Clouds, the closest of which is about 180,000 litas from the Galactic Center. At this distance or beyond, the orbits of most halo objects will be destroyed by Magellanic clouds. Consequently, such objects are likely to be ejected from the vicinity of the Milky Way.
and independent planets
The question of the size of the Milky Way is the question of how large galaxies are in general. Both gravitational microlensing and planetary transit observations indicate that there are at least as many planets tied to stars as there are stars in the Milky Way. And microlensing measurements indicate that there are more independent planets not tied to host stars than there are stars themselves. According to the Meilin Way, there is at least one planet per star, resulting in about 100-400 billion.
In order to understand the structure and size of our galaxy, scientists often conduct various analyzes of this kind, constantly updating and revising outdated data. For example, another analysis of Kepler's data in January 2013 found that there are at least 17 billion Earth-sized exoplanets in the Milky Way. On November 4, 2013, astronomers reported, based on data from the Kepler space mission, that up to 40 billion Earth-sized planets could exist within the range of stars and red dwarfs suitable for the Sun in the Milky Way region, 11 billion of these estimated planets could revolve around sun-like stars. According to a 2016 study, the closest such planet could be 4.2 light years away. Such Earth-sized planets may be more numerous than gas giants... In addition to exoplanets, "exokomets", comets outside the solar system have also been discovered and may be common in the Milky Way. The sizes of stars and galaxies can vary.
The space that we are trying to study is a vast and endless space, in which there are tens, hundreds, thousands of trillions of stars, united in certain groups. Our Earth does not live by itself. We are part of solar system, which is a small particle and is part of the Milky Way - a larger space formation.
Our Earth, like other planets of the Milky Way, our star named the Sun, like other stars of the Milky Way, move in the Universe in a certain order and occupy designated places. Let's try to understand in more detail what is the structure of the Milky Way, and what are the main features of our galaxy?
The origin of the Milky Way
Our galaxy has its own history, like other areas of outer space, and is the product of a catastrophe on a universal scale. The main theory of the origin of the Universe, which today dominates the scientific community, is the Big Bang. The model that perfectly characterizes the Big Bang theory is the chain nuclear reaction at the microscopic level. Initially, there was some kind of substance, which, due to certain reasons, in an instant began to move and exploded. It is not worth talking about the conditions that led to the onset of the explosive reaction. This is far from our understanding. Now formed 15 billion years ago as a result of the cataclysm, the Universe is a huge, endless polygon.
The primary products of the explosion were at first the accumulations and clouds of gas. In the future, under the influence of gravitational forces and other physical processes the formation of larger objects of a universal scale took place. Everything happened very quickly in cosmic terms, over billions of years. First there was the formation of stars, which formed clusters and later merged into galaxies, the exact number of which is unknown. In its composition, galactic matter is hydrogen and helium atoms in the company of other elements, which are building material for the formation of stars and other space objects.
It is not possible to say exactly where the Milky Way is in the Universe, since the center of the universe is not known exactly.
Due to the similarity of the processes that formed the Universe, our galaxy is very similar in structure to many others. By its type, it is a typical spiral galaxy, a type of object that is widespread in the Universe in a huge variety. In terms of its size, the galaxy is in the golden mean - not small and not huge. Our galaxy has much more smaller neighbors in the stellar house than those who have colossal dimensions.
The age of all galaxies that exist in outer space is the same. Our galaxy is practically the same age as the Universe and is 14.5 billion years old. Over this huge period of time, the structure of the Milky Way has repeatedly changed, and this is happening today, only imperceptibly, in comparison with the pace of earthly life.
The story with the name of our galaxy is curious. Scientists believe the name Milky Way is legendary. This is an attempt to connect the location of the stars in our sky with the ancient Greek myth about the father of the gods Kronos, who devoured his own children. The last child, who faced the same sad fate, turned out to be thin and was given to the nurse for fattening. During feeding, a spray of milk fell into the sky, thus creating a milk path. Subsequently, scientists and astronomers of all times and peoples agreed that our galaxy is indeed very similar to the milk road.
The Milky Way is currently in the middle of its development cycle. In other words, the cosmic gas and matter for the formation of new stars are coming to an end. The stars that exist are still quite young. As in the story with the Sun, which may turn into a Red Giant in 6-7 billion years, our descendants will observe the transformation of other stars and the entire galaxy as a whole into a red sequence.
Our galaxy can also cease to exist as a result of the next universal cataclysm. Research topics recent years are guided by the upcoming meeting of the Milky Way with our nearest neighbor - the Andromeda galaxy. Probably, the Milky Way, after meeting with the Andromeda galaxy, will disintegrate into several small galaxies. In any case, this will be the reason for the appearance of new stars and the reorganization of the space nearest to us. It remains only to guess what the fate of the Universe and our galaxy is in the distant future.
Astrophysical parameters of the Milky Way
In order to imagine what the Milky Way looks like on the scale of space, it is enough to look at the Universe itself and compare its individual parts. Our galaxy is part of a subgroup, which in turn is part of the Local Group, a larger entity. Here our cosmic metropolis is adjacent to the Andromeda and Triangle galaxies. The trinity is surrounded by more than 40 small galaxies. The local group is already part of an even larger formation and is part of the Virgo supercluster. Some argue that these are only rough guesses about where our galaxy is. The scale of the formations is so huge that it is almost impossible to imagine all this. Today we know the distance to the nearest neighboring galaxies. Other deep sky objects are out of sight. Only theoretically and mathematically their existence is allowed.
The location of the galaxy became known only thanks to rough calculations that determined the distance to the nearest neighbors. The satellites of the Milky Way are dwarf galaxies - the Small and Large Magellanic Clouds. In total, according to scientists, there are up to 14 satellite galaxies that make up the escort of the universal chariot called the Milky Way.
As for the observable world, today there is enough information about how our galaxy looks like. The existing model, and with it the map of the Milky Way, was compiled on the basis of mathematical calculations, data obtained as a result of astrophysical observations. Each cosmic body or fragment of the galaxy takes its place. It is, like in the Universe, only on a smaller scale. The astrophysical parameters of our space metropolis are interesting, and they are impressive.
Our galaxy is a spiral-type galaxy with a bar, which is denoted by the SBbc index on star maps. The diameter of the Milky Way's galactic disk is about 50-90 thousand light years, or 30 thousand parsecs. For comparison, the radius of the Andromeda galaxy is 110 thousand light years on the scale of the Universe. One can only imagine how much larger our neighbor is than the Milky Way. The dimensions of the dwarf galaxies closest to the Milky Way are tens of times smaller than the parameters of our galaxy. Magellanic clouds are only 7-10 thousand light years in diameter. In this huge stellar circulation, there are about 200-400 billion stars. These stars are collected in clusters and nebulae. A significant part of it is the arms of the Milky Way, in one of which our solar system is located.
Everything else is dark matter, clouds of cosmic gas and bubbles that fill interstellar space. The closer to the center of the galaxy, the more stars, the closer outer space becomes. Our Sun is located in a region of space, consisting of smaller space objects located at a considerable distance from each other.
The mass of the Milky Way is 6x1042 kg, which is trillions of times the mass of our Sun. Almost all the stars inhabiting our star country are located in the plane of one disk, the thickness of which, according to various estimates, is 1000 light years. It is not possible to find out the exact mass of our galaxy, since most of the visible spectrum of stars is hidden from us by the arms of the Milky Way. In addition, the mass of dark matter, which occupies vast interstellar spaces, is unknown.
The distance from the Sun to the center of our galaxy is 27 thousand light years. Being at a relative periphery, the Sun is rapidly moving around the center of the galaxy, making a complete revolution in 240 million years.
The center of the galaxy has a diameter of 1000 parsecs and consists of a nucleus with an interesting sequence. The center of the core has the shape of a bulge in which the largest stars and a cluster of hot gases are concentrated. It is this region that emits a huge amount of energy, which collectively is more than the billions of stars that make up the galaxy emit. This part of the core is the most active and brightest part of the galaxy. There is a bar along the edges of the nucleus, which is the beginning of the arms of our galaxy. Such a bridge arises as a result of the colossal force of gravity caused by the rapid speed of rotation of the galaxy itself.
Considering the central part of the galaxy, the following fact looks paradoxical. Scientists long time could not understand what is in the center of the Milky Way. It turns out that in the very center of the stellar country called the Milky Way, there is a supermassive black hole with a diameter of about 140 km. It is there that most of the energy released by the galactic nucleus goes, it is in this bottomless abyss that stars dissolve and die. The presence of a black hole in the center of the Milky Way indicates that all the processes of formation in the Universe should end sometime. Matter will turn into antimatter and everything will happen again. How this monster will behave after millions and billions of years, the black abyss is silent, which indicates that the processes of absorption of matter are only gaining strength.
From the center, there are two main arms of the galaxy - the Shield of the Centaur and Perseus. These structural formations were named after the constellations located in the sky. In addition to the main arms, the galaxy is surrounded by 5 more small arms.
Near and distant future
The arms born by the core of the Milky Way unwind in a spiral, filling outer space with stars and cosmic material. An analogy with space bodies that revolve around the sun in our star system... A huge mass of stars, large and small, clusters and nebulae, space objects of various sizes and nature, revolves on a giant carousel. All of them create a wonderful picture of the starry sky, which a person has been looking at for more than one thousand years. Studying our galaxy, you should know that the stars in the galaxy live according to their own laws, being today in one of the arms of the galaxy, tomorrow they will begin their journey in the other direction, leaving one arm and flying to the other.
Earth in the Milky Way galaxy is far from the only planet suitable for life. It is just a particle of dust, the size of an atom, which is lost in the vast starry world of our galaxy. There can be a huge number of such planets, similar to Earth, in the galaxy. It is enough to imagine the number of stars that somehow have their own stellar planetary systems. Other life may be far away, at the very edge of the galaxy, tens of thousands of light years away, or, conversely, be present in neighboring regions that are hidden from us by the arms of the Milky Way.