The cosmos that we are trying to study is a vast and boundless space in which there are tens, hundreds, thousands of trillions of stars united in certain groups. Our Earth does not live on its own. We are part of the solar system, which is a small particle and part of the Milky Way - a larger cosmic entity.

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 the allotted 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?

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 that dominates the scientific community today is the Big Bang. The model that perfectly characterizes the Big Bang theory is the chain model. nuclear reaction at the microscopic level. Initially, there was some kind of substance, which, due to certain reasons, in an instant set in motion 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 a cataclysm, the Universe is a huge, endless polygon.

The primary products of the explosion were at first accumulations and clouds of gas. Later, 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 by cosmic standards, over billions of years. First there was the formation of stars, which formed clusters and later coalesced 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 the building material for the formation of stars and other space objects.

Say exactly where in the universe it is Milky Way, is not possible, since the center of the universe is not exactly known.

Due to the similarity of the processes that formed the Universe, our galaxy is very similar in its structure to many others. By its type, this is a typical spiral galaxy, a type of objects that is common in the Universe in a huge variety. In terms of size, the galaxy is in the golden mean - not small and not huge. Our galaxy has many more smaller neighbors in a stellar home than those who are colossal in size.

The age of all galaxies that exist in outer space is the same. Our galaxy is almost the same age as the Universe and has an age of 14.5 billion years. During this vast 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 history with the name of our galaxy is curious. Scientists believe that 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, splashes of milk fell into the sky, thereby creating a milk path. Subsequently, scientists and astronomers of all times and peoples agreed that our galaxy is really very similar to a milky road.

The Milky Way is currently in the middle of its development cycle. In other words, cosmic gas and matter for the formation of new stars are coming to an end. The existing stars 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 the red sequence.

Our galaxy may also cease to exist as a result of another universal cataclysm. Research topics recent years they are guided by the forthcoming meeting of the Milky Way with our closest neighbor, the Andromeda galaxy, in the distant future. It is likely that the Milky Way, after meeting with the Andromeda galaxy, will break up into several small galaxies. In any case, this will be the reason for the emergence of new stars and the reconstruction of the space closest to us. It remains only to guess what is the fate of the Universe and our galaxy 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 space metropolis is adjacent to the Andromeda and Triangulum galaxies. Surrounding the trinity are 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 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 approximate 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 what our galaxy looks like. The existing model, and with it the map of the Milky Way, was compiled on the basis of mathematical calculations obtained from astrophysical observations. Each cosmic body or fragment of the galaxy takes its place. It's like 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 on star maps is denoted by the index SBbc. The diameter of the galactic disk of the Milky Way 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 the Milky Way is our neighbor. The dimensions of the dwarf galaxies closest to the Milky Way are ten times smaller than the parameters of our galaxy. Magellanic clouds have a diameter of only 7-10 thousand light years. In this huge stellar cycle, 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 tighter it gets space. 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 that inhabit our stellar 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 know 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 that occupies vast interstellar spaces is unknown.

The distance from the Sun to the center of our galaxy is 27 thousand light years. Being on the 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 is 1000 parsecs in diameter and consists of a core 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 area that distinguishes great amount energy, which in aggregate is more than the billions of stars that make up the galaxy radiate. This part of the core is the most active and brightest part of the galaxy. Along the edges of the core there is a jumper, 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 rotation of the galaxy itself.

Considering the central part of the galaxy, the following fact looks paradoxical. Scientists for a long time could not understand what is at the center of the Milky Way. It turns out that in the very center of a starry country called the Milky Way, a supermassive black hole has settled down, the diameter of which is about 140 km. It is there that most of the energy released by the core of the galaxy goes, it is in this bottomless abyss that the stars dissolve and die. The presence of a black hole at the center of the Milky Way indicates that all processes of formation in the Universe must someday end. Matter will turn into antimatter and everything will repeat again. How this monster will behave in millions and billions of years, the black abyss is silent, which indicates that the processes of absorption of matter are only gaining momentum.

Two main arms of the galaxy extend from the center - 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 from the core of the Milky Way, spiral outward, filling outer space with stars and cosmic material. An analogy with cosmic bodies that revolve around the Sun in our star system is appropriate here. A huge mass of stars, large and small, clusters and nebulae, cosmic objects of various sizes and nature, spins 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. When studying our galaxy, you should know that the stars in the galaxy live according to their own laws, being in one of the arms of the galaxy today, tomorrow they will start their journey in the other direction, leaving one arm and flying into another.

Earth in the Milky Way galaxy is far from the only planet suitable for life. This is just a particle of dust, the size of an atom, which was lost in the vast stellar 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.

Divide by social groups, our Milky Way galaxy will belong to a strong "middle class". So, it belongs to the most common type of galaxy, but at the same time it is not average in size or mass. There are more galaxies that are smaller than the Milky Way than those that are larger than it. Our "star island" also has at least 14 satellites - other dwarf galaxies. They are doomed to circle the Milky Way until they are consumed by it, or fly away from an intergalactic collision. Well, so far this is the only place where life certainly exists - that is, we are with you.

But still the Milky Way remains the most mysterious galaxy in the Universe: being on the very edge of the "star island", we see only a part of its billions of stars. And the galaxy is completely invisible - it is covered with dense sleeves of stars, gas and dust. The facts and secrets of the Milky Way will be discussed today.

Our galaxy. Mysteries of the Milky Way

To some extent, we know more about distant star systems than we do about our own galaxy, the Milky Way. It is more difficult to study its structure than the structure of any other galaxies, because it has to be studied from the inside, and much is not so easy to see. Interstellar dust clouds absorb the light emitted by myriads of distant stars.

Only with the development of radio astronomy and the advent of infrared telescopes, scientists were able to understand how our galaxy works. But many details remain unclear to this day. Even the number of stars in the Milky Way is estimated quite roughly. The newest electronic directories give numbers from 100 to 300 billion stars.

Not so long ago, it was believed that our Galaxy has 4 large arms. But in 2008, astronomers at the University of Wisconsin published the results of processing some 800,000 infrared images taken by the Spitzer space telescope. Their analysis showed that the Milky Way has only two arms. As for the other arms, they are only narrow side branches. So, the Milky Way is a spiral galaxy with two arms. It should be noted that most of the known spiral galaxies also only two sleeves.

“Thanks to the Spitzer telescope, we have the opportunity to rethink the structure of the Milky Way,” said astronomer Robert Benjamin of the University of Wisconsin, speaking at a conference of the American Astronomical Society. “We are refining our understanding of the Galaxy in the same way that centuries ago, the discoverers, traveling around the globe, refined and rethought previous ideas about what the Earth looks like.”

Since the early 1990s, infrared observations have been increasingly changing our knowledge of the structure of the Milky Way, because infrared telescopes make it possible to look through gas and dust clouds and see what is inaccessible to conventional telescopes.

2004 - the age of our galaxy was estimated at 13.6 billion years. It arose shortly after. Initially, it was a diffuse gas bubble containing mainly hydrogen and helium. Over time, it turned into a huge spiral galaxy in which we now live.

general characteristics

But how did the evolution of our galaxy proceed? How did it form - slowly or, on the contrary, very quickly? How was it saturated with heavy elements? How the shape of the Milky Way and its chemical composition? Detailed answers to these questions have yet to be given by scientists.

The length of our Galaxy is about 100,000 light years, and the average thickness of the galactic disk is about 3,000 light years (the thickness of its convex part - the bulge - reaches 16,000 light years). However, in 2008, Australian astronomer Brian Gensler, after analyzing the results of observations of pulsars, suggested that the galactic disk is probably twice as thick as is commonly believed.

Is our galaxy big or small by cosmic standards? For comparison: the extent of the Andromeda Nebula, the nearest large galaxy to us, is approximately 150,000 light-years.

In late 2008, researchers determined using radio astronomy that the Milky Way was spinning faster than previously thought. Judging by this indicator, its mass is approximately one and a half times higher than it was commonly believed. According to various estimates, it varies from 1.0 to 1.9 trillion solar masses. Again, for comparison: the mass of the Andromeda nebula is estimated at the least at 1.2 trillion solar masses.

The structure of galaxies

Black hole

So, the Milky Way is not inferior in size to the Andromeda Nebula. “We should no longer treat our galaxy as the little sister of the Andromeda Nebula,” said astronomer Mark Reid of the Smithsonian Center for Astrophysics at Harvard University. At the same time, since the mass of our Galaxy is greater than expected, its attractive force is also higher, which means that the probability of its collision with other galaxies in our vicinity also increases.

Our Galaxy is surrounded by a globular halo, reaching 165,000 light-years across. Astronomers sometimes refer to the halo as the "galactic atmosphere." It contains approximately 150 globular clusters, as well as a small number of ancient stars. The rest of the halo space is filled with rarefied gas and dark matter. The mass of the latter is estimated at about a trillion solar masses.

The spiral arms of the Milky Way contain huge amounts of hydrogen. This is where stars continue to be born. Over time, young stars leave the arms of galaxies and "move" into the galactic disk. However, the most massive and brightest stars do not live long enough, therefore they do not have time to move away from their birthplace. It is no coincidence that the arms of our Galaxy glow so brightly. Most of the Milky Way is made up of small, not very massive stars.

The central part of the Milky Way is located in the constellation Sagittarius. This area is surrounded by dark gas and dust clouds, beyond which nothing can be seen. Only since the 1950s, using the means of radio astronomy, have scientists been able to gradually see what lurks there. A powerful radio source, called Sagittarius A, was discovered in this part of the Galaxy. As observations have shown, a mass is concentrated here that exceeds the mass of the Sun by several million times. The most acceptable explanation for this fact is only one: at the center of our Galaxy is located.

Now, for some reason, she has given herself a break and is not particularly active. The influx of matter here is very scarce. Maybe in time the black hole will have an appetite. Then it will again begin to absorb the veil of gas and dust surrounding it, and the Milky Way will add to the list of active galaxies. It is possible that before this, stars will begin to rapidly emerge in the center of the Galaxy. Similar processes are likely to be repeated regularly.

2010 - American astronomers using the Fermi Space Telescope, designed to observe sources of gamma radiation, discovered two mysterious structures in our Galaxy - two huge bubbles emitting gamma radiation. The diameter of each of them is on average 25,000 light years. They scatter from the center of the Galaxy in the northern and southern directions. May be, we are talking about the streams of particles that once emitted a black hole located in the middle of the Galaxy. Other researchers believe that we are talking about gas clouds that exploded during the birth of stars.

There are several dwarf galaxies around the Milky Way. The most famous of them are the Large and Small Magellanic Clouds, which are associated with milky way a kind of hydrogen bridge, a huge plume of gas that stretches behind these galaxies. It is called the Magellanic Stream. Its length is about 300,000 light years. Our Galaxy is constantly engulfing the nearest dwarf galaxies, in particular the Sagitarius Galaxy, which is located at a distance of 50,000 light-years from the galactic center.

It remains to add that the Milky Way and the Andromeda Nebula are moving towards each other. Presumably in 3 billion years, both galaxies will merge together, forming a larger elliptical galaxy, which has already been called the Milky Honey.

Origin of the Milky Way

Andromeda's nebula

For a long time it was believed that the Milky Way formed gradually. 1962 - Olin Eggen, Donald Linden-Bell and Allan Sandage proposed a hypothesis that became known as the ELS model (it was named after the initial letters of their surnames). According to her, a homogeneous cloud of gas once slowly rotated in place of the Milky Way. It resembled a ball and reached a diameter of approximately 300,000 light years, and consisted mainly of hydrogen and helium. Under the influence of gravity, the protogalaxy contracted and became flat; at the same time, its rotation accelerated noticeably.

For almost two decades, this model suited scientists. But new observational results have shown that the Milky Way could not have arisen as theorists prescribed it.

According to this model, the halo is formed first, and then the galactic disk. But there are also very ancient stars in the disk, for example, the red giant Arcturus, whose age is more than 10 billion years, or numerous white dwarfs of the same age.

Both in the galactic disk and in the halo, globular clusters, which are younger than the ELS model allows. Obviously, they are absorbed by our later Galaxy.

Many stars in the halo rotate in a different direction than the Milky Way. Maybe they, too, were once outside the Galaxy, but then they were drawn into this "stellar whirlwind" - like a random swimmer in a whirlpool.

1978 - Leonard Searle and Robert Zinn proposed their own model for the formation of the Milky Way. It was designated as "Model SZ". Now the history of the Galaxy has become noticeably more complicated. Not so long ago, her youth, in the view of astronomers, was described as simply as in the opinion of physicists - a straightforward forward movement. The mechanics of what was happening was clearly visible: there was a homogeneous cloud; it consisted only of evenly spread gas. Nothing by its presence complicated the calculations of theorists.

Now, instead of one huge cloud in the visions of scientists, several small, bizarrely scattered clouds appeared at once. Stars were visible among them; however, they were located only in the halo. Inside the halo, everything was seething: the clouds collided; gas masses were mixed and compacted. Over time, a galactic disk formed from this mixture. New stars began to appear in it. But this model was subsequently criticized.

It was impossible to understand what connected the halo and the galactic disk. This thickening disk and the sparse stellar envelope around it had little in common. Even after Searle and Zinn made their model, it turned out that the halo rotates too slowly to form a galactic disk from it. Judging by the distribution of chemical elements, the latter arose from protogalactic gas. Finally, the angular momentum of the disk turned out to be 10 times higher than that of the halo.

The whole secret is that both models contain a grain of truth. The trouble is that they are too simple and one-sided. Both of them now seem to be fragments of the same recipe by which the Milky Way was created. Eggen and his colleagues read a few lines from this recipe, Searle and Zinn a few others. Therefore, trying to re-imagine the history of our Galaxy, we now and then notice familiar lines that have already been read once.

Milky Way. computer model

So, it all started shortly after the Big Bang. “Today, it is commonly believed that fluctuations in the density of dark matter gave rise to the first structures, the so-called dark halos. Thanks to the force of gravity, these structures did not fall apart, ”says German astronomer Andreas Burkert, author of a new model for the birth of the Galaxy.

Dark halos have become embryos - nuclei - of future galaxies. Around them, under the influence of gravity, gas accumulated. A homogeneous collapse occurred, as described by the ELS model. Already 500-1000 million years after the Big Bang, gas clusters surrounding dark halos became the "incubators" of stars. Small protogalaxies appeared here. In dense clouds of gas, the first globular clusters arose, because stars were born here hundreds of times more often than anywhere else. Protogalaxies collided and merged with each other - this is how large galaxies were formed, including our Milky Way. Today it is surrounded by dark matter and a halo of single stars and their globular clusters, these ruins of a universe that is over 12 billion years old.

There were many very massive stars in protogalaxies. In less than a few tens of millions of years, most of them exploded. These explosions enriched the gas clouds with heavy chemical elements. Therefore, in the galactic disk, not such stars were born as in the halo - they contained hundreds of times more metals. In addition, these explosions generated powerful galactic vortices that heated up the gas and swept it out of the protogalaxies. There was a separation of gas masses and dark matter. This was the most important stage in the formation of galaxies, not previously taken into account in any model.

At the same time, dark halos collided with each other more and more often. Moreover, protogalaxies were stretched out or disintegrated. These catastrophes are reminiscent of the chains of stars preserved in the halo of the Milky Way from the time of "youth". By studying their location, it is possible to evaluate the events that took place in that era. Gradually, a vast sphere formed from these stars - the halo we see. As it cooled, gas clouds penetrated into it. Their angular momentum was preserved, so they did not shrink into a single point, but formed a rotating disk. All this happened over 12 billion years ago. The gas was now compressed as described in the ELS model.

At this time, the "bulge" of the Milky Way is also formed - its middle part, resembling an ellipsoid. The bulge is made up of very old stars. It probably arose during the merger of the largest protogalaxies, which held the gas clouds the longest. In the middle of it were neutron stars and tiny black holes - relics of exploding supernovae. They merged with each other, simultaneously absorbing gas flows. Perhaps this is how the huge black hole was born, which is now in the center of our galaxy.

The history of the Milky Way is much more chaotic than previously thought. Our own Galaxy, impressive even by cosmic standards, was formed after a series of impacts and mergers - after a series of cosmic catastrophes. Traces of those ancient events can still be found today.

So, for example, not all stars in the Milky Way revolve around the galactic center. Probably, over the billions of years of its existence, our Galaxy has "absorbed" many fellow travelers. Every tenth star in the galactic halo is less than 10 billion years old. By that time, the Milky Way had already formed. Perhaps these are the remains of once captured dwarf galaxies. A group of British scientists from the Astronomical Institute (Cambridge), led by Gerard Gilmour, calculated that the Milky Way could obviously absorb from 40 to 60 Carina-type dwarf galaxies.

In addition, the Milky Way attracts huge masses of gas towards itself. So, in 1958, Dutch astronomers noticed many small spots in the halo. Believe it or not, they were gas clouds, which consisted mainly of hydrogen atoms and raced towards the galactic disk.

Our Galaxy will not moderate its appetite in the future. Perhaps it will absorb the nearest dwarf galaxies - Fornax, Carina and, probably, Sextans, and then merge with the Andromeda Nebula. Around the Milky Way - this insatiable "star cannibal" - will become even more deserted.

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The Milky Way is the galaxy in which the Earth is located. solar system and all individual stars visible to the naked eye. Refers to barred spiral galaxies.

The Milky Way, together with the Andromeda Galaxy (M31), the Triangulum Galaxy (M33) and more than 40 dwarf satellite galaxies - its own and Andromeda - form the Local Group of galaxies, which is part of the Local Supercluster (Virgo Supercluster).

Discovery history

Discovery of Galileo

The Milky Way revealed its secret only in 1610. It was then that the first telescope was invented, which was used by Galileo Galilei. The famous scientist saw through the device that the Milky Way is a real cluster of stars, which, when viewed with the naked eye, merged into a continuous faintly twinkling band. Galileo even succeeded in explaining the heterogeneity of the structure of this band. It was caused by the presence in the celestial phenomenon of not only star clusters. There are also dark clouds. The combination of these two elements creates an amazing image of the night phenomenon.

Discovery of William Herschel

The study of the Milky Way continued into the 18th century. During this period, his most active researcher was William Herschel. The famous composer and musician was engaged in the manufacture of telescopes and studied the science of the 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 also located. Herschel even drew a schematic plan of his discovery. In the figure, the star system was depicted as a millstone and had an elongated irregular shape. The sun at the same time was inside this ring that surrounded our world. This is how all scientists represented our Galaxy until the beginning of the last century.

It was not until the 1920s that the work of Jacobus Kaptein saw the light of day, in which the Milky Way was described in the most detailed way. 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 is the Milky Way?

When studying galaxies, Edwin Hubble classified them into various types of 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 Kapetin and others were erroneous, because the measurements were based on observations using radiation waves in the visible region of the spectrum. Trumpler came to the conclusion 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. Because of this, in order to accurately image the stars and star clusters within the Milky Way, astronomers had to find a way to see through the dust.

In the 1950s, the first radio telescopes were invented. Astronomers have discovered that hydrogen atoms emit radiation in radio waves, and that such radio waves can penetrate dust in the Milky Way. Thus, it became possible to see the spiral arms of this galaxy. To do this, we used the marking of stars by analogy with marks when measuring distances. Astronomers realized that O and B stars could serve to achieve this goal.

Such stars have several features:

• brightness– they are highly visible 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 move far from their birthplace.

Astronomers can use radio telescopes to accurately match the positions of O and B stars and, based on the Doppler shifts in the radio spectrum, determine their speed. After performing such operations on many stars, scientists were able to produce combined radio and optical maps of the Milky Way's spiral arms. Each arm is named after the constellation that exists in 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 mix cake dough with an electric mixer. These density waves are thought to have caused the spiral character of the galaxy.

Thus, by examining the sky at different wavelengths (radio, infrared, visible, ultraviolet, X-ray) using various ground-based and space telescopes, one can obtain various images of the Milky Way.

Doppler effect. Just as the high pitched sound of a fire truck siren gets lower as the vehicle moves away, the movement of the stars affects the wavelengths of light that reach Earth from them. This phenomenon is called the Doppler effect. We can measure this effect by measuring the lines in the star's spectrum and comparing them to the spectrum of a standard lamp. The degree of Doppler shift indicates how fast the 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 star's spectrum shifts to the blue end, then the star is moving towards us; if in the red direction, it moves away.

Structure of the Milky Way

If we carefully consider the structure of the Milky Way, we will see the following:

1. galactic disk. Most of the stars in the Milky Way are concentrated here.

The disk itself is divided into the following parts:

• The nucleus is the center of the disk;
• Arcs - areas around the nucleus, including directly the areas above and below the plane of the disk.
• Spiral arms are areas that protrude outward from the center. Our solar system is located in one of the spiral arms of the Milky Way.

1. globular clusters. Several hundred of them are scattered above and below the plane of the disk.
2. Halo. This is a large, dim region that surrounds the entire galaxy. The halo consists 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 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 exceeds 12 billion years. The central, densest part of the halo within a few thousand light-years of the center of the Galaxy is called bulge(translated from English "thickening"). The halo as a whole rotates very slowly.

Compared to halo disk spins much faster. It looks like two plates folded at the edges. The diameter of the disk of the Galaxy is about 30 kpc (100,000 light years). The thickness is about 1000 light years. The 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. The mass of the disk is 150 billion times the mass of the Sun (1.99*1030 kg). Young stars and star clusters are concentrated in the disk. There are many bright and hot stars among them. The gas in the disk of the Galaxy is unevenly distributed, forming giant clouds. Main chemical element in our galaxy is hydrogen. About 1/4 of it consists of helium.

One of the most areas of interest The galaxy is considered to be its center, or core located in the direction of the constellation Sagittarius. The visible radiation of the central regions of the Galaxy is completely hidden from us by powerful layers of absorbing matter. Therefore, it began to be studied 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, regions of ionized hydrogen and numerous sources of infrared radiation are noted, indicating star formation taking place there. At the very center of the Galaxy, the existence of a massive compact object is assumed - a black hole with a mass of about a million solar masses.

One of the most notable formations is spiral branches (or sleeves). They gave the name to this type of objects - spiral galaxies. Along the arms, the youngest stars are mainly concentrated, many open star clusters, as well as chains of dense clouds of interstellar gas in which stars continue to form. In contrast to 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, which are concentrated along long spirals. According to modern concepts, spiral arms are associated with compression waves propagating across the disk of the galaxy. Passing through the compression regions, the matter of the disk 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 sections of two spiral branches that are about 3 thousand light years away 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 in the middle between these spiral arms. True, relatively close (by galactic standards) from us, in the constellation of 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 in about 200 million years. This means that for the entire time of its existence, the Earth flew 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 compression wave, which forms the spiral arm, moves in the given region. This situation is generally unusual for the Galaxy: the spiral arms rotate with a constant angular velocity like the spokes of a wheel, and the movement of the stars, as we have seen, obeys a completely different pattern. Therefore, almost the entire stellar population of the disk either gets inside the spiral branch or leaves it. The only place where the speeds of stars and spiral arms coincide is the so-called corotation circle, and it is on it that the Sun is located!

For the Earth, this circumstance is extremely favorable. After all, violent processes occur in the spiral branches, generating powerful radiation, destructive for all living things. And no atmosphere could protect him from it. 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 originate and survive on Earth.

For a long time, the position of the Sun among the stars was considered the most ordinary. Today we know that this is not so: in a certain 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 location of the stars

On a cloudless night sky, the Milky Way is visible from anywhere on our planet. However, only a part of the Galaxy, which is a system of stars located inside the Orion arm, is accessible to the human eye. What is the Milky Way? The definition in space of all its parts becomes most understandable if we consider the star map. In this case, it becomes clear that the Sun, illuminating the Earth, is located almost on the disk. This is almost the edge of the Galaxy, where the distance from the nucleus is 26-28 thousand light years. Moving at a speed of 240 kilometers per hour, the Luminary spends 200 million years on one revolution around the core, so that for the entire time of its existence it traveled across the disk, rounding the core, only thirty times. Our planet is in the so-called corotation circle. This is a place in which the speed of rotation 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 only arise on that planet, near which there is a small number of stars. Our Earth is such a planet. It is located on the periphery of the Galaxy, in its most peaceful place. That is why on our planet for several billion years there was no global cataclysms that 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.

• Triangulum Galaxy. With a mass of about 5% of that 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 is 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 is undergoing active star formation as tidal interactions with our galaxy cause gas to collapse and give rise to new, hot and large stars in the universe.
• Small Magellanic Cloud, NGC 3190 and NGC 6822. All of them have masses from 0.1% to 0.6% of the Milky Way (and it is not clear which one is larger) and all three are independent galaxies. Each contains over a billion solar masses of material.
• Elliptical galaxies M32 and M110. They may be "only" satellites of Andromeda, but each of them has more than a billion stars, and they can even exceed the masses of 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 attached 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 passes, galaxies interact gravitationally. They not only pull together due to gravitational attraction, but also interact tidally. We usually talk about tides in the context of the Moon pulling on Earth's oceans and creating tides, and this is partly true. But from the point of view of the galaxy, the tides are a less noticeable process. The part of a small galaxy that is close to a large one will attract more gravitational force, and the part that is further away will experience less attraction. As a result, the small galaxy will stretch out and eventually break apart under the influence of gravity.

Not large galaxies, which are part of our local group, including both Magellanic clouds and dwarf elliptical galaxies, will be torn apart in this way, and their material will be included in the large galaxies with which they merge. “So what,” you say. After all, this is not quite 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 the galaxies into a gravitational dance that will lead to a big merger. Although this process will take billions of years, spiral structure both galaxies will be destroyed, resulting in the creation of a single, giant elliptical galaxy at the core of our local group: the Mammals.

A small percentage of the stars will be ejected during such a merger, but the majority will remain unharmed, and there will be a large burst of star formation. Eventually, the rest of the galaxies in our local group will also be sucked in, leaving one big giant galaxy to gobble up 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 from each other. But even this cannot be called death, because the galaxy will remain. And for a while it will be. But the galaxy is made up of stars, dust and gas, and everything will eventually come to an end.

Across the Universe, galactic mergers will take place over tens of billions of years. During the same time, dark energy will pull them all over 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 in them will live. 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 each galaxy—albeit with 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 are left with brown dwarfs (failed stars) that accidentally merge, re-ignite nuclear fusion and create starlight for tens of trillions of years.

When the last star goes out tens of quadrillion years in the future, there will still be some mass left in the galaxy. So this can not 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 momentum between them.
• Objects with low mass are ejected from the galaxy, and objects with higher mass sink into the center, losing speed.
• Over a sufficiently long period of time, most of the mass will be ejected, and only a small part of the remaining mass will be firmly attached.

At the very center of these galactic remnants will be a supermassive black hole, in every galaxy, and the rest of the galactic objects will orbit a larger 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 everything it can reach. At the center of Mlecomeda there will be an object hundreds of millions of times more massive than our Sun.

But will it end too?

Thanks to the phenomenon of Hawking radiation, even these objects will one day decay. It will take about 10 80 to 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 randomly dissociate, depending on the properties of this very matter. Without any matter, there will be nothing that we once called the local group, the Milky Way and other dear names.

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, stole straw from the ancestor of the Assyrians, Barsham, in a harsh winter and disappeared into the sky. When he walked with his prey across the sky, he dropped straws on his way; from them a light trail was formed in the sky (in Armenian “Straw thief’s road”). The myth about scattered straw is also spoken of by Arabic, Jewish, Persian, Turkish and Kyrgyz names (Kirg. samanchynyn jolu- the path of the strawman) of this phenomenon. The inhabitants of Wallachia believed that Venus stole this straw from St. Peter.

Buryat

According to Buryat mythology, good forces create the world, modify the universe. Thus, the Milky Way arose from the milk that Manzan Gurme drew from her breast and splashed out after Abai Geser, who had deceived her. According to another version, the Milky Way is a "seam of the sky" sewn up after the stars fell out of it; on it, like on a bridge, tengri walk.

Hungarian

According to Hungarian legend, Attila will descend the Milky Way if the Székelys are in danger; the stars represent sparks from the hooves. Milky Way. accordingly, it is called the "road of warriors."

ancient greek

Etymology of the word Galaxias (Γαλαξίας) and its association with milk (γάλα) reveal two similar ancient greek myth. One of the legends tells about the mother's milk spilled across the sky of the goddess Hera, who was breastfeeding Hercules. When Hera learned 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 has a plan to save her sixth child, the 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. The milk spilled from Rhea's chest on a bare rock was subsequently called the Milky Way.

Indian

The ancient Indians considered the Milky Way to be the milk of an evening red cow passing through the sky. In the Rig Veda, the Milky Way is called Aryaman's Throne Road. 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 Inca astronomy (which is reflected in their mythology) in the sky were the dark sections of the Milky Way - a kind of "constellation" in the terminology of Andean cultures: Lama, Lama Cub, Shepherd, Condor, Partridge, Toad, Snake, Fox; as well as the stars: the Southern Cross, the Pleiades, Lyra and many others.

Ketskaya

In the Ket myths, similarly to the Selkup ones, the Milky Way is described as the road of one of the three mythological characters: the Son of Heaven (Esya), who went hunting to the western side of the sky and froze there, the hero Albe, who pursued the evil goddess, or the first shaman Dokh, who climbed this road to the sun.

Chinese, Vietnamese, Korean, Japanese

In the mythologies of the Sinosphere, the Milky Way is called and compared to a river (in Vietnamese, Chinese, Korean and Japanese the name "silver river" is retained. The Chinese also sometimes called the Milky Way the "Yellow Road", after the color of the straw.

Indigenous peoples of North America

The Hidatsa and the Eskimos call the Milky Way "Ash". Their myths speak 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 dirt and silt raised by the belly of a turtle floating in the sky. Eskimos from the Bering Strait - that these are the traces of the Creator Raven 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 unattended cornmeal 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. The Ctunah called the Milky Way "the dog's tail", the Blackfoot called it the "wolf road". 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 to be the Tama-rereti boat. The nose 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 already late, and he was far from home. There were no stars in the sky, and, fearing that Tanif might attack, Tama-rereti began to throw sparkling pebbles into the sky. The heavenly 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, Erzya, Kazakh

The Finnish name is Fin. Linnunrata- means "The Way of the Birds"; the Lithuanian name has a similar etymology. Estonian myth also connects the Milky ("bird's") Way with bird flight.

The Erzya name is "Kargon Ki" ("Crane Road").

The Kazakh name is “Kus Zholy” (“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 picking stars from the Sagittarius Dwarf Galaxy and the Magellanic Clouds;
• The Milky Way moves in space with an acceleration of 550 km / s with respect to the background radiation;
• Lurking at the galactic center is the supermassive black hole Sagittarius A*. By mass, it is 4.3 million times greater than the solar one;
• 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;
• In 5 billion years, a collision with the Andromeda galaxy is expected.

In our galaxy. This is associated with huge distances in space and the complexity of observations with subsequent analysis of the data obtained. To date, scientists have managed to detect and register about 50 billion luminaries. A more advanced technique allows us to explore the distant corners of space and obtain new information about objects.

Estimation and search for supergiants in space

Modern astrophysics in the process of space exploration is constantly faced with a large number of questions. The reason for this is the gigantic size visible universe, about fourteen billion light years. Sometimes, when observing a star, it is quite difficult to estimate the distance to it. Therefore, before setting out on a journey in search of determining which is the largest star in our galaxy, it is necessary to understand the level of difficulty in observing space objects.

Previously, until the beginning of the twentieth century, it was believed that our galaxy is one. Visible other galaxies were classified as nebulae. But Edwin Hubble dealt a crushing blow to the ideas of the scientific world. He argued that there are a large number of galaxies, and ours is not the largest.

Space is incredibly huge

The distances to the nearest galaxies are enormous. reach hundreds of millions of years. It is quite problematic for astrophysicists to determine which is the largest star in our galaxy.

Therefore, it is even more difficult to talk about other galaxies with trillions of stars, at a distance of a hundred or more million light years. In the process of research, new objects are opened. The discovered stars are compared and the most unique and largest are determined.

Supergiant in the constellation Scutum

The name of the big star in our galaxy - UY Shield, a red supergiant. This is a variable which varies from 1700 to 2000 solar diameters.

Our brain is not capable of representing such quantities. Therefore, for a complete idea of ​​what size is the largest star in the galaxy, it is necessary to compare with the values ​​\u200b\u200bthat are understandable to us. Our solar system is suitable for comparison. The size of the star is so large that if it is placed in the place of our Sun, then the boundary of the supergiant will be in the orbit of Saturn.

And our planet and Mars will be inside the star. The distance to this "monster" of space is about 9600 light years.

The largest star in the galaxy - UY Shield - can only be conditionally considered a "king". The reasons are obvious. One of them is huge cosmic distances and space dust making it difficult to obtain accurate data. Another problem is directly related to physical properties supergiants. With a diameter 1700 times larger than ours heavenly body, the largest star in our galaxy, is only 7-10 times as massive as it is. It turns out that the density of the supergiant is millions of times less than the air around us. Its density is comparable to the Earth's atmosphere at an altitude of about a hundred kilometers above sea level. Therefore, it is rather problematic to determine exactly where the boundaries of a star end and its “wind” begins.

On the this moment the largest star in our galaxy is at the end of its evolutionary cycle. It expanded (the same process will happen with our Sun at the end of evolution) and began to actively burn helium and a number of other elements heavier than hydrogen. After a few million years, the largest star in the galaxy - UY Scuti - will turn into a yellow supergiant. And in the future - into a bright blue variable, and possibly into a Wolf-Rayet star.

Along with the "king" - the supergiant UY Scuti - about ten stars with similar sizes can be noted. They include VY Big Dog, Cepheus A, NML Cygnus, WOH G64 VV and several others.

It is known that all the largest stars are short-lived and very unstable. Such stars can exist both for millions of years and for several millennia, ending their life cycle in the form of a supernova or a black hole.

The largest star in the galaxy: the search continues

Observing serious changes over the past twenty years, it is worth assuming that over time our understanding of the possible parameters of supergiants will differ from previously known ones. And it is quite possible that in the coming years another supergiant will be discovered, with a larger mass or size. And new discoveries will prompt scientists to revise previously accepted dogmas and definitions.