Milky Way(computer model). Barred spiral galaxy. Two of the four arms dominate.

The Milky Way (or Galaxy, with a capital letter) - in which they are located, and all the individual ones 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, which is included in the (Virgo Supercluster).

Etymology

Name Milky Way common in Western culture and is a tracing paper from lat. via lactea"milk road", which, in turn, is a tracing paper from other Greek. ϰύϰλος γαλαξίας "milky circle". Name Galaxy formed by analogy with other Greek. γαλαϰτιϰός "milk". According to ancient Greek legend, Zeus decided to make his son Hercules, born of a mortal woman, immortal, and for this he placed him on his sleeping wife Hera so that Hercules would drink divine milk. Hera, waking up, saw that she was not feeding her own child, and pushed him away from her. A jet of milk splashed from the breast of the goddess turned into the Milky Way.

In the Soviet astronomical school, the Milky Way galaxy was simply called "our Galaxy" or "the Milky Way system"; the phrase "Milky Way" was used to refer to the visible stars that optically constitute the Milky Way to the observer.

Outside of Western culture, there are many other names for the Milky Way. The word "Way" often remains, the word "Milky" is replaced by other epithets.

Structure of the Galaxy

The diameter of the Galaxy is about 30 thousand parsecs (about 100,000 light years, 1 quintillion kilometers) with an estimated average thickness of about 1000 light years. The galaxy contains, according to the lowest estimate, about 200 billion stars (modern estimates range from 200 to 400 billion). Most of the stars are in the form of a flat disk. As of January 2009, the mass of the Galaxy is estimated at 3·10 12 solar masses, or 6·10 42 kg. The new minimum estimate determines the mass of the galaxy as only 5·10 11 solar masses. Most of the mass of the Galaxy is contained not in stars and interstellar gas, but in a nonluminous halo from .

Disk

It wasn't until the 1980s that astronomers suggested that the Milky Way is a barred spiral galaxy rather than a regular spiral galaxy. This assumption was confirmed in 2005 by Lyman Spitzer, who showed that the central bar of our galaxy is larger than previously thought.

According to scientists, the galactic disk, prominent in different sides near the galactic center, has a diameter of about 100,000 light years. Compared to the halo, the disk rotates noticeably faster. The speed of its rotation 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 disk rotation made it possible to estimate its mass; it turned out that it is 150 billion times greater than M ☉ .

Near the plane of the disk, young stars and star clusters are concentrated, the age of which does not exceed several billion years. They form the so-called flat component. There are a lot of bright and hot stars among them. The gas in the disk of the Galaxy is also concentrated mainly near its plane. It is distributed unevenly, forming numerous gas clouds - from gigantic, heterogeneous clouds with a length of over several thousand light-years to small clouds no larger than a parsec.

Core

The galactic center of the Milky Way in infrared.

In the middle part of the Galaxy there is a bulge called bulge (bulge - thickening), which is about 8,000 parsecs across. The center of the nucleus of the Galaxy is located in the constellation Sagittarius (α = 265°, δ = −29°). The distance from the Sun to the center of the Galaxy is 8.5 kiloparsecs (2.62 10 17 km, or 27,700 light years). In the center of the Galaxy, apparently, there is a supermassive (Sagittarius A) (about 4.3 million M ☉) around which, presumably, a black hole of average mass from 1000 to 10,000 M ☉ rotates and with an orbital period of about 100 years and several thousand relatively small. Their combined gravitational action on neighboring stars causes the latter to move along unusual trajectories. There is an assumption that most galaxies have supermassive black holes in their core.

The central regions of the Galaxy are characterized by a strong concentration of stars: each cubic parsec near the center contains many thousands of them. Distances between stars are tens and hundreds of times less than in the vicinity of the Sun. As in most other galaxies, the distribution of mass in the Milky Way is such that the orbital velocity of most of the stars in the Galaxy does not depend to a large extent on their distance from the center. Further from the central bridge to the outer circle, the usual speed of rotation of stars is 210-240 km / s. Thus, such a velocity distribution, which is not observed in the solar system, where different orbits have significantly different revolution velocities, is one of the prerequisites for the existence of dark matter.

The galactic bar is thought to be about 27,000 light-years long. This bar passes through the center of the galaxy at an angle of 44 ± 10 degrees to the line between our Sun and the center of the galaxy. It consists predominantly of red stars, which are considered very old. The bar is surrounded by a ring called the "Five Kiloparsec Ring". This ring contains most of the Galaxy's molecular hydrogen and is an active star-forming region in our Galaxy. If we observe from the Andromeda galaxy, then the galactic bar of the Milky Way would be a bright part of it.

In 2016, Japanese astrophysicists reported the discovery of a second giant black hole at the Galactic Center. This black hole is located 200 light years from the center of the Milky Way. An observed astronomical object with a cloud occupies a region of space with a diameter of 0.3 light years, and its mass is 100 thousand solar masses. The nature of this object has not yet been precisely established - it is a black hole or another object.

Sleeves

Arms of the Galaxy

The galaxy belongs to the class of spiral galaxies, which means that the Galaxy has spiral sleeves located in the plane of the disk. The disk is in halo spherical shape, and around it is a spherical crown. The solar system is located at a distance of 8.5 thousand parsecs from the galactic center, near the plane of the Galaxy (the offset to the North Pole of the Galaxy is only 10 parsecs), on the inner edge of the arm called Orion arm. This arrangement makes it impossible to observe the shape of the sleeves visually. New data from observations of molecular gas (CO) suggest that our Galaxy has two arms starting at a bar in the inner part of the Galaxy. In addition, there are a couple of sleeves in the inner part. Then these arms pass into the four-arm structure observed in the line of neutral hydrogen in the outer parts of the Galaxy.

Halo

The vicinity of the Milky Way and its halo.

The galactic halo has a spherical shape, extending beyond the galaxy by 5-10 thousand light years, and a temperature of about 5 10 5 K. The galactic disk is surrounded by a spheroid halo consisting of old stars and globular clusters, 90% of which are located at a distance of less than 100,000 light years from the center of the galaxy. However, in recent times Several globular clusters have been found, such as PAL 4 and AM 1, more than 200,000 light-years from the center of the galaxy. 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, low-mass stars. They occur both singly and in the form of globular clusters, which can contain up to a million stars. The age of the population of the spherical component of the Galaxy exceeds 12 billion years, it is usually considered the age of the Galaxy itself.

While the galactic disk contains gas and dust, which makes it difficult for visible light to pass through, the spheroid component does not. Active star formation occurs in the disk (especially in the spiral arms, which are areas of increased density). In the halo, star formation has ended. Open clusters also occur predominantly in the disk. It is believed that the main mass of our galaxy is dark matter, which forms a halo of dark matter with a mass of approximately 600 - 3000 billion M☉. The dark matter halo is concentrated towards the center of the galaxy.

Stars and stellar halo clusters move around the center of the Galaxy in very elongated orbits. Since the rotation of individual stars is somewhat random (that is, the speeds of neighboring stars can be in any direction), the halo as a whole rotates very slowly.

The history of the discovery of the Galaxy

Most celestial bodies are combined into various rotating systems. So, revolving around the Earth, the giant planets form their own, rich in bodies, systems. For more high level, the Earth and the rest revolve around the Sun. A natural question arose: isn't the Sun included in an even larger system?

The first systematic study of this issue was carried out in the 18th century by the English astronomer William Herschel. He counted the number of stars in different areas of the sky and found that there is a large circle in the sky (later it was called galactic equator), which divides the sky into two equal parts and on which the number of stars is the largest. In addition, there are more stars, the closer the area of ​​the sky is located to this circle. Finally, it was found that the Milky Way is located on this circle. Thanks to this, Herschel guessed that all the stars we observed form a giant star system, which is flattened towards the galactic equator.

At first it was assumed that all objects are parts of our Galaxy, although even Kant suggested that some nebulae could be galaxies similar to the Milky Way. As early as 1920, the question of the existence of extragalactic objects caused debate (for example, the famous Great Debate between Harlow Shapley and Geber Curtis; the former defended the uniqueness of our Galaxy). Kant's hypothesis was finally proved only in the 1920s, when Ernst Epik and Edwin Hubble managed to measure the distance to some spiral nebulae and show that, by their distance, they cannot be part of the Galaxy.

Location of the Sun in the Galaxy

According to the latest scientific estimates, the distance from the Sun to the galactic center is 26,000 ± 1,400 light years, while according to preliminary estimates, our star should be about 35,000 light years from the bar. This means that 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 200 million years. Thus, for the entire time of its existence, the Earth flew around the center of the Galaxy no more than 30 times.

In the vicinity of the Sun, it is possible to track sections of two spiral arms that are about 3 thousand light years away from us. According to the constellations where these areas are observed, they were given the name of the Sagittarius arm and the Perseus arm. The sun is located almost in the middle between these spiral arms. But relatively close to us (by galactic standards), in the constellation of 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 compression 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, so 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 it that the Sun is located.

For the Earth, this circumstance is extremely important, since violent processes occur in the spiral arms, which form powerful radiation that is destructive to 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 been affected by these cosmic cataclysms for hundreds of millions (or even billions) of years. Perhaps that is why life was able to be born and survive on Earth.

Evolution and the future of the Galaxy

Collisions of our Galaxy with other galaxies are possible, including such a large one as the Andromeda galaxy, but specific predictions are still impossible due to ignorance of the transverse velocity of extragalactic objects.

Panorama of the Milky Way taken in Death Valley, USA, 2005.

Panorama of the southern sky, taken near the Paranal Observatory, Chile, 2009.

Our Galaxy - Milky Way

© Vladimir Kalanov
"Knowledge is power".

Considering the night starry sky, you can see a dimly glowing whitish band that crosses the celestial sphere. This diffuse glow comes from both hundreds of billions of stars and the scattering of light by tiny particles of dust and gas in interstellar space. This is our Milky Way galaxy. The Milky Way is a galaxy to which the solar system belongs with its planets, including the Earth. It is visible from anywhere on the earth's surface. The Milky Way forms a ring, so from any point on Earth we see only part of it. The Milky Way, which appears to be a dim, luminous road, is actually made up of a huge number of stars that are not visible individually to the naked eye. He was the first to think about this at the beginning of the 17th century when he pointed a telescope he had made to the Milky Way. What Galileo saw for the first time was breathtaking. In the place of the whitish huge strip of the Milky Way, sparkling clusters of countless stars, visible separately, opened up to his gaze. Today, scientists believe that the Milky Way contains a huge number of stars - about 200 billion.

Rice. one schematic representation our galaxy and its surrounding halo.

The Milky Way is a galaxy consisting of a large flat - the main - disk-shaped body with a diameter exceeding a distance of 100,000 light years. The disk of the Milky Way itself is "relatively thin" - a few thousand light-years thick. Most of the stars are located inside the disk. According to its morphology, the disk is not compact, has a complex structure, inside it there are uneven structures that extend from the core to the periphery of the Galaxy. These are the so-called "spiral arms" of our Galaxy, high-density zones where new stars form from clouds of interstellar dust and gas.

Rice. 2 Center of the Galaxy. Image in conventional colors of the center of the Milky Way.

Explanation of the figure: The light source in the middle is Sagittarius A, an active star-forming zone, located near the galactic core. The center is surrounded by a gaseous ring (pink circle). The outer ring contains molecular clouds (orange) and ionized hydrogen space in pink.

In the central part of the disk of the Milky Way is the galactic nucleus. The core is made up of billions of old stars. The very central part of the core is a very massive region with a diameter of only a few light years, inside which, according to the latest data from astronomical research, there is a supermassive black hole, possibly even several black holes, with masses of about 3 million Suns.

Around the disk of the Galaxy is a spherical halo (crown) containing dwarf galaxies (Large and Small Magellanic Clouds, etc.), globular star clusters, individual stars, groups of stars and hot gas. Some of the individual groups of stars interact with globular clusters and dwarf galaxies. There is a hypothesis, arising from the analysis of the structure of the halo and the trajectories of star clusters, that globular clusters, like the galactic corona itself, can be the remnants of former satellite galaxies absorbed by our Galaxy as a result of earlier interactions and collisions.

According to scientific assumptions, Our Galaxy also contains dark matter, which, perhaps, is much larger than all visible matter in all observation ranges.

On the outskirts of the Galaxy, dense regions of gas with a size of several thousand light years, a temperature of 10,000 degrees and a mass of 10 million Suns have been discovered.

Our Sun is almost on the disk, at a distance of about 28,000 light-years from the center of the Galaxy. In other words, it is located on the periphery, at a distance of almost 2/3 of the galactic radius from the center, which is a distance of about 8 kiloparsecs from the center of our Galaxy.

Rice. 3 The plane of the Galaxy and the plane of the solar system do not coincide, but are at an angle to each other.

The position of the Sun in the Galaxy

The position of the Sun in the Galaxy and its movement are also considered in detail in the "Sun" section of our website (see). To make a complete revolution, the Sun needs about 250 million years (according to some sources, 220 million years), which make up a galactic year (the speed of the Sun is 220 km / s, that is, almost 800,000 km / h!). Every 33 million years, the Sun crosses the galactic equator, then rises above its plane to a height of 230 light-years, and again descends to the equator. It takes about 250 million years for the Sun to make a complete revolution.

Since we are inside the Galaxy and look at it from the inside, its disk turns out to be visible on the celestial sphere as a band of stars (this is the Milky Way), and therefore it is difficult to determine the real three-dimensional spatial structure of the Milky Way from the Earth.

Rice. 4 full sky survey in galactic coordinates taken at 408 MHz (wavelength 73 cm), shown in false colors.

The intensity of radio emission is displayed on a linear color scale from dark blue (lowest intensity) to red (highest intensity). The angular resolution of the map is approximately 2°. Many well-known radio sources are visible along the plane of the galaxy, including supernova remnants of Cassiopeia A and the Crab Nebula.
The complexes of local arms (Cygnus X and Parusa X) surrounded by diffuse radio emission are clearly distinguished. The diffuse radio emission of the Milky Way is mainly the synchrotron emission of cosmic ray electrons during their interaction with magnetic field our Galaxy.

Rice. 5 Two full-sky images from data taken in 1990 by the DIRBE Diffuse Infrared Background Experiment on the COBE satellite.

Both images show strong radiation from the Milky Way. On the top photo shows combined emission data at 25, 60, and 100 micron far infrared wavelengths, shown in blue, green, and red, respectively. This radiation comes from cold interstellar dust. Pale blue background radiation is generated by interplanetary dust in the solar system. The bottom image combines 1.2, 2.2, and 3.4 micron NIR emission data, shown in blue, green, and red, respectively.

New map of the Milky Way

The Milky Way can be classified as spiral galaxy. As already mentioned, it consists of a main body in the form of a flat disk with a diameter of more than 100,000 light years, within which most of the stars are located. The disk has a non-compact structure, and its uneven structure is obvious, starting from the core and spreading to the periphery of the Galaxy. These are the spiral branches of the areas of the highest density of matter, the so-called. spiral arms in which the process of formation of new stars takes place, starting in interstellar gas and dust clouds. Nothing can be said about the cause of the appearance of spiral arms, except that the arms always appear in the numerical simulation of the birth of a galaxy, if sufficiently large mass and moment of rotation are given.

Long touch the cell for a description to appear. To enlarge the image - briefly To return from the image - the return key on the phone or in the browser

A computer-generated new 3D model of the Milky Way with the actual location of hundreds of thousands of nebulae and stars.
© National Geographic Society, Washington D.C. 2005.

Rotation of parts of the galaxy

Parts of the galaxy rotate at different speeds around its center. If we could look at the Galaxy "from above", we would see a dense and bright core, inside which the stars are located very close to each other, as well as arms. In them, the stars are concentrated less compactly.

The direction of rotation of the Milky Way, as well as similar spiral galaxies (indicated on the map in the lower left corner with an increase) is such that the spiral arms, as it were, twist. And here it is necessary to focus on the following specific point. During the existence of the Galaxy (at least 12 billion years, according to any modern estimates), the spiral branches would have to spin around the center of the Galaxy several dozen times! And this is not observed in other galaxies, nor in ours. Back in 1964, Q. Lin and F. Shu from the USA proposed a theory according to which spiral arms are not some material formations, but matter density waves that stand out against the even background of the galaxy, primarily because they are undergoing active star formation, accompanied by the birth of high-luminosity stars. The rotation of the spiral arm has nothing to do with the movement of stars in galactic orbits. At short distances from the core, the orbital velocities of the stars exceed the velocity of the arm, and the stars "flow" into it with inside, but leave from the outside. At large distances, the opposite is true: the sleeve, as it were, runs into the stars, temporarily includes them in its composition, and then overtakes them. As for the bright OB stars that determine the pattern of the arm, they, having been born in the arm, end their relatively short life, not having time to leave the sleeve during its existence.

The gas ring and the movement of stars

According to one of the hypotheses of the structure of the Milky Way, between the center of the Galaxy and the spiral arms there is another so-called. "gas ring" The ring of gas contains billions of solar masses of gas and dust and is the site of active star formation. This area radiates strongly in the radio and infrared range. The study of this formation was carried out using clouds of gas and dust located along the line of sight, and therefore measuring the exact distances to this formation, as well as its exact configuration, is very difficult and there are still two main opinions of scientists about this. According to the first, scientists believe that this formation is not a ring, but grouped spirals. According to another opinion, this formation can be considered ring-shaped. Presumably it is located at a distance between 10 and 16 thousand light years from the center.

There is a special branch of astrophysics that studies the movement of stars in the Milky Way, it is called "stellar kinematics".

To facilitate the task of stellar kinematics, stars are divided into families according to certain features, age, physical data, and location within the Galaxy. For the vast majority of young stars concentrated in spiral arms, the rotation speed (relative to the center of the Galaxy, of course) is several kilometers per second. It is believed that such stars had too little time to interact with other stars, they "did not use" mutual attraction to increase their rotation speed. Middle-aged stars have higher speeds.

Old stars have the fastest speed, located in a spherical halo that surrounds our Galaxy to a distance of 100,000 light-years from the center. Their speed exceeds 100 km / s (as in globular star clusters).

In the inner regions, where they are densely concentrated, the Galaxy in its movement manifests itself similarly to a solid body. In these areas, the speed of rotation of stars is directly proportional to their distance from the center. The rotation curve will look like a straight line.

On the periphery, a Galaxy in motion no longer resembles a solid body. In this part, it is not densely "populated" with celestial bodies. The "rotation curve" for the peripheral regions will be "Keplerian", similar to the rule about the unequal speed of the planets in the solar system. The speed of rotation of stars decreases with distance from the center of the galaxy.

star clusters

Not only stars are in constant motion, but also other celestial objects that inhabit the Milky Way: these are open and globular star clusters, nebulae, etc. Special study deserves the movement of globular star clusters - dense formations, which include hundreds of thousands of old stars. These clusters have a distinct spherical shape, they move around the center of the Galaxy in elongated elliptical orbits inclined to its disk. Their average speed is about 200 km/s. Globular star clusters cross the disk at intervals of several million years. Being fairly densely grouped formations, they are relatively stable and do not fall apart under the influence of the attraction of the plane of the Milky Way. The situation is different with open star clusters. They include several hundreds or thousands of stars, and they are mainly in spiral arms. The stars there are not so close to each other. It is believed that open star clusters tend to decay after a few billion years of existence. Globular star clusters are old in time of formation, they can have an age of the order of ten billion years, open clusters are much younger (the count goes from a million to tens of millions of years), very rarely their age exceeds one billion years.

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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.

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. A model that perfectly characterizes the theory big bang- chain 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 that formed clusters and later coalesced into galaxies, exact amount which are unknown. In its composition, galactic matter is hydrogen and helium atoms in the company of other elements that are building material for the formation of stars and other space objects.

It is not possible to say exactly where in the Universe the Milky Way is located, 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. Existing Model, and with it the map of the Milky Way, is 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'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 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 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 region that releases a huge amount of 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 long time could not figure out what was 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.

We live in a galaxy called the Milky Way. Our planet Earth is only a grain of sand in the Milky Way galaxy. In the course of filling the site every now and then, moments appear that it would seem that it was necessary to write about a long time ago, but then they forgot, then they didn’t have time or switched to something else. Today we will try to fill one of these niches. Today our topic is the Milky Way galaxy..

Once people thought that the center of the World is the Earth. Over time, this opinion was recognized as erroneous and began to be considered the center of the entire Sun. But then it turned out that the luminary, which gives life to all life on the blue planet, is by no means the center of outer space, but only a tiny grain of sand in the boundless ocean of stars.

space, galaxy, milky way

The cosmos visible to the human eye includes myriads of stars. All of them are combined into a huge star system, which is called very beautifully and intriguingly - the Milky Way galaxy. From Earth, this celestial splendor is observed in the form of a wide whitish band, dimly glowing on the celestial sphere.

It stretches across the entire northern hemisphere and crosses the constellations of Gemini, Auriga, Cassiopeia, Chanterelle, Cygnus, Taurus, Eagle, Arrow, Cepheus. Encircles the southern hemisphere and passes through the constellations of Unicorn, Southern Cross, Southern Triangle, Scorpio, Sagittarius, Sails, Compasses.

If you arm yourself with a telescope and look through it at the night sky, then the picture will be different. A wide whitish stripe will turn into countless luminous stars. Their faint distant alluring light will tell without words about the greatness and boundless expanses of the Cosmos, will make you hold your breath and realize all the insignificance and worthlessness of momentary human problems.

The milky way is called galaxy or a giant star system. Estimates are currently leaning more and more towards the figure of 400 billion stars in the Milky Way. All these stars move in closed orbits. They are connected to each other by the forces of gravity, and most of them have planets. Stars and planets form stellar systems. Such systems are with one star (solar system), double (Sirius - two stars), triple (alpha Centauri). There are four, five stars, and even seven.

Milky Way in the form of a disk

The structure of the Milky Way

All this countless variety of stellar systems that make up the Milky Way is not scattered across outer space at random, but is combined into a colossal formation that has the shape of a disk with a thickening in the middle. The diameter of the disk is 100,000 light years (one light year corresponds to the distance that light travels in a year, which is about 10¹³ km) or 30,659 parsecs (one parsec is 3.2616 light years). The thickness of the disk is equal to several thousand light-years, and its mass exceeds the mass of the Sun by 3 × 10¹² times.

The mass of the Milky Way is composed of a mass of stars, interstellar gas, dust clouds and a halo, which has the shape of a huge sphere consisting of rarefied hot gas, stars and dark matter. Dark matter is represented as a set of hypothetical space objects, the masses of which make up 95% of the entire Universe. These mysterious objects are invisible and do not react in any way to modern technical means detection.

The presence of dark matter can only be guessed from its gravitational effect on visible clusters of suns. There are not so many of those available for observation. The human eye, even when amplified by the most powerful telescope, can only see two billion stars. The rest of outer space is hidden by huge impenetrable clouds, consisting of interstellar dust and gas.

Thickening ( bulge) in the central part of the disk of the Milky Way is called the Galactic center or core. In it, billions of old stars move in very elongated orbits. Their mass is very large and is estimated at 10 billion solar masses. The core size is not that impressive. It is 8000 parsecs across.

galactic core is a brightly shining ball. If earthlings could observe it in the sky, then their eyes would see a giant luminous ellipsoid, which in size would be a hundred times larger than the moon. Unfortunately, this most beautiful and magnificent sight is inaccessible to people because of the powerful gas and dust clouds that obscure the galactic center from planet Earth.

At a distance of 3000 parsecs from the center of the Galaxy, there is a gas ring 1500 parsecs wide and with a mass of 100 million solar masses. It is here, as expected, that the central region of the formation of new stars is located. Gas sleeves about 4 thousand parsecs long scatter from it. At the very center of the nucleus is black hole, with a mass of more than three million suns.

galactic disk structurally heterogeneous. It has separate high-density zones, which are spiral arms. In them, the continuous process of the formation of new stars continues, and the arms themselves stretch along the core and, as it were, go around it in a semicircle. There are currently five of them. These are the Cygnus arm, the Perseus arm, the Centaurus arm and the Sagittarius arm. In the fifth sleeve - arm of Orion- The solar system is located.

Please note - this is a spiral structure. Increasingly, people notice this structure literally everywhere. Many will be surprised, but the flight path of our Earth with you also there is a spiral!

It is separated from the galactic core by 28,000 light years. Around the center of the Galaxy, the Sun with its planets rushes at a speed of 220 km / s, and makes a complete revolution in 220 million years. True, there is another figure - 250 million years.

The solar system is located just below the galactic equator, and in its orbit it does not move smoothly and calmly, but as if bouncing. Once every 33 million years, it crosses the galactic equator and rises above it at a distance of 230 light years. Then it descends back to repeat its rise through the next interval of 33 million years.

The galactic disk rotates, but it does not rotate as a single body. The nucleus rotates faster, the spiral arms in the disk plane are slower. Naturally, a logical question arises: why the spiral arms do not twist around the center of the Galaxy, but always remain the same shape and configuration for already 12 billion years (the age of the Milky Way is estimated at such a figure).

There is a theory that quite plausibly explains this phenomenon. She considers spiral arms not as material objects, but as matter density waves arising against the galactic background. This is caused by star formation and the birth of high luminosity stars. In other words, the rotation of the spiral arms has nothing to do with the motion of stars in their galactic orbits.

The latter, only, pass through the arms either ahead of them in speed, if they are closer to the Galactic center, or behind, if they are located in the peripheral regions of the Milky Way. The outlines of these spiral waves give the brightest stars, which have a very short life and manage to live it without leaving the sleeve.

As can be seen from all of the above, the Milky Way is the most complex space formation, but it is not limited to the surface of the disk. Around there is a huge cloud of spherical shape ( halo). It consists of: rarefied hot gases, individual stars, globular star clusters, dwarf galaxies and dark matter. There are dense clouds of gas on the outskirts of the Milky Way. Their length is several thousand light years, the temperature reaches 10,000 degrees, and the mass is equal to at least ten million suns.

Neighbors of the Milky Way Galaxy

In the boundless Cosmos, the Milky Way is far from alone. At a distance of 772 thousand parsecs from it is an even larger star system. It's called Andromeda Galaxy(maybe more romantic - Andromeda Nebula). It has been known since ancient times as "a small celestial cloud, easily distinguishable in dark night". Even at the beginning of the 17th century, religious astronomers believed that "in this place the crystal firmament is thinner than usual, and the light of the kingdom of heaven pours through it."

The Andromeda Nebula is the only galaxy that can be seen in the sky with the naked eye. It is seen as a small oval luminous spot. The light in it is unevenly distributed: the central part is brighter. If you strengthen the eye with a telescope, then the speck will turn into a giant star system, the diameter of which is 150 thousand light years. This is one and a half times the diameter of the Milky Way.

dangerous neighbor

But Andromeda does not differ in size from the galaxy in which the solar system exists. Back in 1991, the planetary camera space telescope them. Hubble recorded that it had two nuclei. Moreover, one of them is smaller and revolves around another, larger and brighter, gradually collapsing under the influence of the tidal forces of the latter. This slow agony of one of the cores suggests that it is the remnant of some other galaxy, swallowed up by Andromeda.

For many, it will be an unpleasant surprise to learn that the Andromeda Nebula is moving towards the Milky Way, and, therefore, towards the Solar System. The approach speed is about 140 km/s. Accordingly, the meeting of the two stellar giants will take place somewhere in 2.5-3 billion years. It will not be a meeting on the Elbe, but it will not be a global catastrophe on a cosmic scale either..

Two galaxies will simply merge into one. But which one will dominate - here the scales are tilted in favor of Andromeda. It has more mass, besides, it already has experience of absorbing other galactic systems.

As for the solar system, then the forecasts vary. The most pessimistic one indicates that the Sun with all the planets will simply be thrown into intergalactic space, that is, there will be no place for it in the new formation.

But maybe that's for the best. After all, everything shows that the Andromeda Galaxy is a kind of bloodthirsty monster devouring its own kind. Having swallowed the Milky Way and destroyed its core, the Nebula will turn into a huge Nebula and continue its journey through the expanses of the Universe, eating more and more new galaxies. The end result of this journey will be the collapse of an incredibly swollen, super-giant star system.

The Andromeda Nebula will disintegrate into countless small stellar formations, exactly repeating the fate of the huge empires of human civilization, which first grew to unprecedented proportions, and then collapsed with a roar, unable to withstand the burden of their own greed, self-interest and lust for power.

But do not bother with the events of future tragedies. It is better to consider another galaxy, which is called Triangulum Galaxies. It is spread out in the expanses of the Universe at a distance of 730 thousand parsecs from the Milky Way and is twice as small in size as the latter, and at least seven times smaller in mass. That is, this is an ordinary mediocre galaxy, of which there are a great many in space.

All these three star systems, coupled with a few dozen more dwarf galaxies, are part of the so-called Local Group, which is part of Virgo Superclusters- a huge stellar formation, the size of which is 200 million light years.

The Milky Way, the Andromeda Nebula and the Triangulum Galaxy have a lot of common features. All of them belong to the so-called spiral galaxies. Their disks are flat and consist of young stars, open star clusters, and interstellar matter. In the center of each disk there is a thickening (bulge). The main feature, of course, is the presence of bright spiral arms containing many young and hot stars.

The cores of these galaxies are also similar to the cluster of old stars and gas rings in which new stars are born. An invariable attribute of the central part of each nucleus is the presence of a black hole with a very large mass. It has already been mentioned that the mass of the black hole of the Milky Way corresponds to more than three million masses of the Sun.

Black holes- one of the most impenetrable mysteries of the universe. Of course, they are watched, they are studied, but these mysterious formations are in no hurry to reveal their secrets. It is known that black holes have a very high density, and their gravitational field is so powerful that even light cannot escape from them.

But any space body that is in the zone of influence of one of them ( event threshold) will be immediately "swallowed" by this terrible universal monster. What will further fate"unfortunate" - unknown. In a word, it is easy to get into a black hole, but it is impossible to get out of it.

A lot of black holes are scattered across the expanses of the Cosmos, some of them have a mass many times greater than the mass of a black hole in the center of the Milky Way. But this does not at all mean that the monster “native” to the solar system is more harmless than its larger counterparts. It is also voracious and bloodthirsty, and is a compact (12.5 light-hours in diameter) and powerful source of X-rays.

The name of this mysterious object Sagittarius A. Its mass has already been named - more than 3 million masses of the Sun, and the gravitational trap (threshold of events) of the baby is measured at 68 astronomical units (1 AU is equal to the average distance of the Earth from the Sun). It is within these limits that the border of his bloodthirstiness and deceit lies in relation to various cosmic bodies, which, for a number of reasons, frivolously cross it.

Someone probably naively thinks that the baby is content with random victims - nothing like that: he has permanent source nutrition. This is an S2 star. It revolves around the black hole in a very compact orbit - a complete revolution is only 15.6 years. The maximum distance of S2 from the terrible monster lies within 5 light days, and the minimum is only 17 light hours.

Under the influence of the tidal forces of a black hole, part of its substance is torn off from a star doomed to be slaughtered and flies with great speed towards this terrible cosmic monster. As it approaches, the substance passes into a state of incandescent plasma and, radiating a farewell bright radiance, disappears forever in an insatiable invisible abyss.

But that's not all: the insidiousness of a black hole has no limits. Next to it there is another, less massive and dense black hole. Its task is to adjust the stars, planets, interstellar dust and gas clouds to its more powerful counterpart. All this also turns into plasma, emits bright light and disappears into nowhere.

However, not all scientists, despite such a convincing bloody interpretation of events, are of the opinion that black holes exist. Some argue that this is an unknown mass, driven under a cold dense shell. It has a huge density and bursts from within the surface compressing it with incredible force. Such education is called gravastar is a gravitational star.

Under this model, they try to fit the entire Universe, thus explaining its expansion. Proponents of this concept argue that outer space is a giant bubble inflated by an unknown force. That is, the entire Cosmos is a huge gravastor, in which smaller models of gravastors coexist, periodically absorbing individual stars and other formations.

The absorbed bodies are, as it were, thrown into other outer spaces, which are essentially invisible, since they do not release light from under an absolutely black shell. Maybe gravastors are other dimensions or parallel worlds? A concrete answer to this question will not be found for a very, very long time.

But not only the presence or absence of black holes occupies the minds of space explorers. Much more interesting and exciting are reflections on the existence of intelligent life in other star systems of the Universe.

The Sun that gives life to earthlings rotates among many other suns in the Milky Way. Its disk is visible from the Earth in the form of a pale shining band encircling the celestial sphere. These are distant billions and billions of stars, many of which have their own planetary systems. Is there really not at least one among the countless number of these planets on which intelligent beings live - brothers in mind?

The most reasonable assumption is that Earth-like life can arise on a planet that revolves around a star of the same class as the Sun. There is such a star in the sky, moreover, it is located in the star system closest to the earth's body. This is Alpha Centauri A, located in the constellation Centaurus. From the ground, it is visible to the naked eye, and its distance from the Sun is 4.36 light years.

It would be nice, of course, to have reasonable neighbors right next to you. But the desired does not always coincide with the actual. Finding signs of an extraterrestrial civilization, even at a distance of some 4-6 light years, is a rather difficult task with the current advances in technology. Therefore, it is premature to talk about the existence of any mind in the constellation Centaurus.

Nowadays, it is only possible to send radio signals into space, hoping that someone unknown will respond to the call of human intelligence. The most powerful radio stations in the world have been persistently and non-stop engaged in such activities since the first half of the 20th century. As a result, the level of radio emission of the Earth has increased significantly. The blue planet began to differ sharply in its radiation background from all other planets in the solar system.

Signals from Earth cover outer space with a radius of at least 90 light years. On the scale of the universe, this is a drop in the ocean, but as you know, this smallness wears away a stone. If somewhere far, far away in the Cosmos there is highly developed intelligent life, then, in any case, it must sometime turn its attention to the increased radiation background in the depths of the Milky Way galaxy, and to the radio signals coming from there. Such an interesting phenomenon cannot leave indifferent the inquisitive minds of aliens.

Accordingly, an active search for signals from the Cosmos has been established. But the dark abyss is silent, which indicates that within the Milky Way there are most likely no intelligent beings ready to make contact with the inhabitants of planet Earth, or their technical development is at a very primitive level. True, another thought arises, which suggests that a highly developed civilization, or civilizations, exists, but sends some other signals to the expanses of the Galaxy, which cannot be caught by terrestrial technical means.

Progress on the blue planet is steadily developing and improving. Scientists are developing new, completely different ways of transmitting information over long distances. All this can have a positive effect. But we must not forget that the expanses of the universe are limitless. There are stars whose light reaches the Earth after billions of years. In fact, a person sees a picture of the distant past when he observes such a space object through a telescope.

It may turn out that the signal received by earthlings from space will turn out to be the voice of a long-disappeared extraterrestrial civilization that lived at a time when neither the solar system nor the Milky Way existed yet. The return message from the Earth will get to the aliens, who were not even in the project at the time when it was sent.

Well, we must take into account the laws of harsh reality. In any case, the search for intelligence in distant galactic worlds cannot be stopped. Unlucky current generations, lucky future ones. Hope in this case will never die, and perseverance and perseverance will undoubtedly pay off handsomely.

But it seems quite real and close to the development of galactic space. Already in the next century, fast and elegant spaceships will fly to the nearest constellations. The astronauts on their boards will observe through the windows not the planet Earth, but the entire solar system. She will be seen by them in the form of a distant, bright star. But it will not be the cold soulless brilliance of one of the countless suns of the Galaxy, but the native radiance of the Sun, near which mother earth will rotate as an invisible, soul-warming speck.

Very soon, the dreams of science fiction writers, reflected in their works, will become an ordinary everyday reality, and a walk along the Milky Way is a rather boring and tedious task, like, for example, a trip in a subway car from one end of Moscow to another.