• Repair
• Repair
• Interior Design
• About everything
• About plumbing

Andromeda is the closest galaxy to the Milky Way. Collision of the Milky Way and Andromeda. For everyone and everything

Scientists have known for some time that the Milky Way Galaxy is not the only one in the universe. In addition to our galaxy, which is part of the Local Group - a collection of 54 galaxies and dwarf galaxies - we are also part of a larger entity known as the Virgo Cluster of galaxies. So, we can say that the Milky Way has many neighbors.

Of these, most people believe that the Andromeda Galaxy is our closest galactic cohabitant. But truth be told, Andromeda is the closest spiral Galaxy, but not the nearest galaxy at all. This distinction falls to the point of forming what is actually within the Milky Way itself, but a dwarf galaxy, which is known by the name Canis Major Gnome Galax (aka. Canis Major).

This star formation is located about 42,000 light-years from the galactic center and only 25,000 light-years from our solar system. This puts it closer to us than the center of our own galaxy, which is 30,000 light-years away from the solar system.

Prior to its discovery, astronomers believed that the Sagittarius Dwarf Galaxy was the closest galactic formation to our own. At 70,000 light-years from Earth, this galaxy was determined in 1994 to be closer to us than the Large Magellanic Cloud, a dwarf galaxy 180,000 light-years away that previously held the title of our nearest neighbor.

That all changed in 2003, when the Canis Major dwarf galaxy was discovered by the 2 Micron Panoramic Survey (2MASS), during an astronomical mission that took place between 1997 and 2001.

With the help of telescopes located on the MT. Hopkins Observatory in Arizona (for the Northern Hemisphere) and at the Inter-American Observatory in Chile for the Southern Hemisphere, astronomers have been able to conduct a comprehensive survey of the sky in infrared light that is not blocked by gas and dust as brutally as visible light.

Because of this technique, astronomers have been able to detect a very significant density of class M giant stars in the sky occupied by constellations big dog, as well as several other associated structures that make up this type of star, two of which have the appearance of wide, swooning arcs (as seen in the image above).

The abundance of M-class stars is what made the formation easy to detect. These cool, "red dwarfs" aren't very bright compared to other classes of stars, and can't even be seen with the naked eye. However, they are very bright in infrared, and have appeared in large numbers.

In addition to its composition, the galaxy has a near-elliptical shape and is believed to contain as many stars as the Sagittarius dwarf elliptical galaxy, the previous contender for the closest galaxy to our location in the Milky Way.

In addition to the dwarf galaxy, a long string of stars is visible trailing behind it. This complex, ring structure - sometimes called the Monoceros ring - warps around the galaxy three times. The stream was first detected in the early 21st century by astronomers conducting the Sloan Digital Sky Survey.

It was during the investigation of this ring of stars, and closely spaced groups of globular clusters similar to those associated with Sagittarius dwarf elliptical galaxies, that the Canis Major dwarf galaxy was discovered.

The current theory is that this galaxy was fused (or swallowed up) into the Milky Way Galaxy. Other globular clusters orbiting the center of the Milky Way as a satellite - that is, either NGC 1851, NGC 1904, NGC 2298 and NGC 2808 - are believed to have been part of the big dog of the dwarf galaxy prior to its accretion.

The discovery of this galaxy, and subsequent analysis of the stars associated with it, provides some support for the current theory that galaxies can grow in size by swallowing their smaller neighbors. The Milky Way became what it is now, eating up other galaxies like a big dog, and it continues to do so today. And since the stars of the canis major dwarf galaxy are technically already part of the Milky Way, it is, by definition, the closest galaxy to us.

Astronomers also believe that canis major dwarf galaxies are pulling apart the gravitational field of the more massive Milky Way galaxy in the process. The main body of the galaxy is already extremely degraded, and this process will continue as it travels around and through our Galaxy. During the accretion is likely to end with a large dog dwarf galaxy deposited 1 billion stars per 200 m0 400 billion, which are already part of the Milky Way.

Prior to its discovery in 2003, it was the Sagittarius dwarf elliptical galaxy that held the position of being the closest galaxy to our own. At a distance of 75,000 light years. This dwarf galaxy, which consists of four globular clusters that measure about 10,000 light-years in diameter, was discovered in 1994. Prior to this, the Large Magellanic Cloud was thought to be our nearest neighbor.

The Andromeda Galaxy (M31) is the closest spiral galaxy to us. Although - gravitationally - connected to the Milky Way, it is still not the nearest Galaxy - 2 million light-years away. Andromeda is currently approaching our galaxy at a speed of about 110 kilometers per second. In about 4 billion years, the Andromeda Galaxy is expected to merge to form a single Super Galaxy.

GALAXIES, "extragalactic nebulae" or "island universes," are giant star systems that also contain interstellar gas and dust. The solar system is part of our galaxy - the Milky Way. All space to the limits where the most powerful telescopes can penetrate is filled with galaxies. Astronomers number at least a billion of them. The nearest galaxy is located at a distance of about 1 million light years from us. years (10 19 km), and to the most distant galaxies registered by telescopes - billions of light years. The study of galaxies is one of the most ambitious tasks of astronomy.

Historical reference. The brightest and closest outer galaxies to us - the Magellanic Clouds - are visible to the naked eye in the southern hemisphere of the sky and were known to the Arabs as early as the 11th century, as well as the brightest galaxy in the northern hemisphere - the Great Nebula in Andromeda. With the rediscovery of this nebula in 1612 with the help of a telescope by the German astronomer S. Marius (1570–1624), the scientific study of galaxies, nebulae and star clusters began. Many nebulae were discovered by various astronomers in the 17th and 18th centuries; then they were considered clouds of luminous gas.

The idea of ​​star systems beyond the Galaxy was first discussed by philosophers and astronomers of the 18th century: E. Swedenborg (1688–1772) in Sweden, T. Wright (1711–1786) in England, I. Kant (1724–1804) in Prussia, and .Lambert (1728–1777) in Alsace and W. Herschel (1738–1822) in England. However, only in the first quarter of the 20th century. the existence of "island Universes" was unambiguously proved mainly due to the work of American astronomers G. Curtis (1872-1942) and E. Hubble (1889-1953). They proved that the distances to the brightest, and hence the closest "white nebulae" are much larger than the size of our Galaxy. Between 1924 and 1936, Hubble pushed the frontier of galaxy exploration from nearby systems to the limits of the 2.5-meter telescope at Mount Wilson Observatory, i.e. up to several hundred million light years.

In 1929, Hubble discovered the relationship between the distance to a galaxy and its speed. This relationship, Hubble's law, has become the observational basis of modern cosmology. After the end of World War II, an active study of galaxies began with the help of new large telescopes with electronic light amplifiers, automatic measuring machines and computers. The detection of radio emission from our and other galaxies has given new opportunity to study the Universe and led to the discovery of radio galaxies, quasars and other manifestations of activity in the nuclei of galaxies. Extra-atmospheric observations from the board of geophysical rockets and satellites made it possible to detect x-rays from the nuclei of active galaxies and clusters of galaxies.

Rice. 1. Classification of galaxies according to Hubble

The first catalog of "nebulae" was published in 1782 by the French astronomer C. Messier (1730-1817). This list includes both star clusters and gaseous nebulae in our Galaxy, as well as extragalactic objects. Messier object numbers are still in use today; for example, Messier 31 (M 31) is the famous Andromeda Nebula, the nearest large galaxy observed in the constellation Andromeda.

A systematic survey of the sky, begun by W. Herschel in 1783, led him to the discovery of several thousand nebulae in the northern sky. This work was continued by his son J. Herschel (1792-1871), who made observations in the southern hemisphere at the Cape of Good Hope (1834-1838) and published in 1864 General directory 5 thousand nebulae and star clusters. In the second half of the 19th century. newly discovered objects were added to these objects, and J. Dreyer (1852–1926) in 1888 published New shared directory (New General Catalog - NGC), including 7814 objects. With the publication in 1895 and 1908 of two additional directory-index(IC) the number of discovered nebulae and star clusters exceeded 13 thousand. The designation according to the NGC and IC catalogs has since become generally accepted. So, the Andromeda Nebula is designated either M 31 or NGC 224. A separate list of 1249 galaxies brighter than the 13th magnitude, based on a photographic survey of the sky, was compiled by H. Shapley and A. Ames from the Harvard Observatory in 1932.

This work has been substantially expanded by the first (1964), second (1976), and third (1991) editions. Reference catalog of bright galaxies J. de Vaucouleurs with employees. More extensive, but less detailed catalogs based on viewing photographic sky survey plates were published in the 1960s by F. Zwicky (1898-1974) in the USA and B.A. Vorontsov-Velyaminov (1904-1994) in the USSR. They contain approx. 30 thousand galaxies up to the 15th magnitude. A similar survey of the southern sky was recently completed using the 1-meter Schmidt camera of the European Southern Observatory in Chile and the British 1.2-meter Schmidt camera in Australia.

There are too many galaxies fainter than 15th magnitude to make a list of them. In 1967, the results of counting galaxies brighter than magnitude 19 (to the north of declination 20) were published by C. Shein and K. Virtanen on the plates of the 50-cm astrograph of the Lick Observatory. Such galaxies turned out to be approx. 2 million, not counting those that are hidden from us by the wide dust lane of the Milky Way. And back in 1936, Hubble at the Mount Wilson Observatory counted the number of galaxies up to the 21st magnitude in several small areas distributed evenly over the celestial sphere (to the north of declination 30). According to these data, there are more than 20 million galaxies in the entire sky brighter than the 21st magnitude.

Classification. There are galaxies of various shapes, sizes and luminosities; some of them are isolated, but most have neighbors or satellites that exert a gravitational influence on them. As a rule, galaxies are quiet, but active ones are often found. In 1925, Hubble proposed a classification of galaxies based on their appearance. It was later refined by Hubble and Shapley, then by Sandage, and finally by Vaucouleur. All galaxies in it are divided into 4 types: elliptical, lenticular, spiral and irregular.

Elliptical(E) galaxies have the shape of ellipses in photographs without sharp boundaries and clear details. Their brightness increases towards the center. These are rotating ellipsoids made up of old stars; their apparent shape depends on the orientation to the observer's line of sight. When viewed from the edge, the ratio of the lengths of the short and long axes of the ellipse reaches  5/10 (denoted E5).

Rice. 2 Elliptical Galaxy ESO 325-G004

Lenticular(L or S 0) galaxies are similar to elliptical ones, but, in addition to the spheroidal component, they have a thin, rapidly rotating equatorial disk, sometimes with ring-like structures like the rings of Saturn. Viewed edge-on, lenticular galaxies look more compressed than elliptical ones: the ratio of their axes reaches 2/10.

Rice. 2. The Spindle Galaxy (NGC 5866), a lenticular galaxy in the constellation Draco.

Spiral(S) galaxies also consist of two components - spheroidal and flat, but with a more or less developed spiral structure in the disk. Along the sequence of subtypes Sa, Sb, sc, SD(from "early" to "late" spirals), the spiral arms become thicker, more complex and less twisted, and the spheroid (central condensation, or bulge) decreases. Edge-on spiral galaxies do not have spiral arms, but the galaxy type can be determined from the relative brightness of the bulge and disk.

Rice. 2. An example of a spiral galaxy, the Pinwheel Galaxy (Messier List 101 or NGC 5457)

Wrong(I) galaxies are of two main types: Magellanic type, i.e. type of the Magellanic Clouds, continuing the sequence of spirals from sm before Im, and non-magellanic type I 0, which have chaotic dark dust lanes over a spheroidal or disk structure such as a lenticular or early spiral structure.

Rice. 2. NGC 1427A, an example of an irregular galaxy.

Types L And S are divided into two families and two species, depending on the presence or absence of a passage through the center and crossing the disk linear structure (bar), as well as a centrally symmetric ring.

Rice. 2. Computer model of the Milky Way galaxy.

Rice. 1. NGC 1300, an example of a barred spiral galaxy.

Rice. 1. THREE-DIMENSIONAL CLASSIFICATION OF GALAXIES. Main types: E, L, S, I are in series from E before Im; families of ordinary A and crossed B; kind s And r. The circular diagrams below are a cross-section of the main configuration in the region of spiral and lenticular galaxies.

Rice. 2. BASIC FAMILIES AND TYPES OF SPIRALS on the section of the main configuration in the area Sb.

There are other classification schemes for galaxies based on finer morphological details, but an objective classification based on photometric, kinematic, and radio measurements has not yet been developed.

Compound. Two structural components - a spheroid and a disk - reflect the difference in the stellar population of galaxies, discovered in 1944 by the German astronomer W. Baade (1893–1960).

Population I, present in irregular galaxies and spiral arms, contains blue giants and supergiants of spectral types O and B, red supergiants of classes K and M, and interstellar gas and dust with bright regions of ionized hydrogen. It also contains low-mass main-sequence stars that are visible near the Sun, but indistinguishable in distant galaxies.

Population II, present in elliptical and lenticular galaxies, as well as in the central regions of spirals and in globular clusters, contains red giants from the G5 to K5 class, subgiants, and probably subdwarfs; it contains planetary nebulae and outbursts of novae (Fig. 3). On fig. Figure 4 shows the relationship between the spectral classes (or color) of stars and their luminosity in different populations.

Rice. 3. STAR POPULATIONS. A photo of the spiral galaxy Andromeda Nebula shows that blue giants and supergiants of Population I are concentrated in its disk, and the central part consists of red stars of Population II. The satellites of the Andromeda Nebula are also visible: the galaxy NGC 205 ( at the bottom) and M 32 ( top left). The brightest stars in this photo belong to our galaxy.

Rice. 4. HERTZSHPRUNG-RUSSELL DIAGRAM, which shows the relationship between the spectral class (or color) and the luminosity of stars different type. I: Population I young stars typical of spiral arms. II: aged stars Population I; III: Old Population II stars, typical of globular clusters and elliptical galaxies.

Initially, elliptical galaxies were thought to contain only Population II, and irregular galaxies only Population I. However, it turned out that galaxies usually contain a mixture of two stellar populations in different proportions. A detailed population analysis is only possible for a few nearby galaxies, but measurements of the color and spectrum of distant systems show that the difference in their stellar populations may be more significant than Baade thought.

Distance. The measurement of distances to distant galaxies is based on the absolute distance scale to the stars of our Galaxy. It is installed in several ways. The most fundamental is the method of trigonometric parallaxes, which operates up to distances of 300 sv. years. Other methods are indirect and statistical; they are based on the study of proper motions, radial velocities, brightness, color and spectrum of stars. Based on them, the absolute values ​​of the New and variables of the RR Lyrae type and  Cepheus, which become the primary indicators of the distance to the nearest galaxies where they are visible. Globular clusters, the brightest stars and emission nebulae of these galaxies become secondary indicators and make it possible to determine the distances to more distant galaxies. Finally, the diameters and luminosities of the galaxies themselves are used as tertiary indicators. As a measure of distance, astronomers usually use the difference between the apparent magnitude of an object m and its absolute magnitude M; this value ( m-M) is called the "apparent distance modulus". To know the true distance, it must be corrected for light absorption by interstellar dust. In this case, the error usually reaches 10–20%.

The extragalactic distance scale is revised from time to time, which means that other parameters of galaxies that depend on distance also change. In table. 1 shows the most accurate distances to the nearest groups of galaxies today. To more distant galaxies billions of light years away, distances are estimated with low accuracy by their redshift ( see below: The nature of the redshift).

Luminosity. Measuring the surface brightness of a galaxy gives the total luminosity of its stars per unit area. The change in surface luminosity with distance from the center characterizes the structure of the galaxy. Elliptic systems, as the most regular and symmetrical, have been studied in more detail than others; in general, they are described by a single luminosity law (Fig. 5, A):

Rice. 5. LUMINOSITY DISTRIBUTION OF GALAXIES. A– elliptical galaxies (shown is the logarithm of surface brightness depending on the fourth root of the reduced radius ( r/r e) 1/4 , where r is the distance from the center, and r e is the effective radius containing half of the total luminosity of the galaxy); b– lenticular galaxy NGC 1553; V- three normal spiral galaxies (the outer part of each lines straight, indicating an exponential dependence of luminosity on distance).

Data on lenticular systems is not so complete. Their luminosity profiles (Fig. 5, b) differ from the profiles of elliptical galaxies and have three main regions: core, lens, and envelope. These systems appear to be intermediate between elliptical and spiral systems.

Spirals are very diverse, their structure is complex, and there is no single law for the distribution of their luminosity. However, it seems that in simple spirals far from the core, the surface luminosity of the disk decreases exponentially towards the periphery. Measurements show that the luminosity of the spiral arms is not as high as it seems when looking at photographs of galaxies. The arms add no more than 20% to the luminosity of the disk in blue rays and much less in red ones. The contribution to the luminosity from the bulge decreases from Sa To SD(Fig. 5, V).

By measuring the apparent magnitude of the galaxy m and determining its distance modulus ( m-M), calculate the absolute value M. The brightest galaxies, excluding quasars, M -22, i.e. their luminosity is almost 100 billion times greater than that of the Sun. And the smallest galaxies M10, i.e. luminosity approx. 10 6 solar. Distribution of the number of galaxies by M, called the "luminosity function", - important characteristic the galactic population of the universe, but it is not easy to accurately determine it.

For galaxies selected up to a certain limiting visible magnitude, the luminosity function of each type separately from E before sc almost Gaussian (bell-shaped) with an average absolute value in blue rays M m= 18.5 and dispersion  0.8 (Fig. 6). But late-type galaxies from SD before Im and elliptical dwarfs are fainter.

For a complete sample of galaxies in a given volume of space, for example, in a cluster, the luminosity function grows steeply with decreasing luminosity, i.e. The number of dwarf galaxies is many times greater than the number of giant ones.

Rice. 6. GALAXY LUMINOSITY FUNCTION. A– the sample is brighter than some limiting visible value; b is a full sample in a certain large amount of space. Note the vast majority of dwarf systems with M B< -16.

Size. Since the stellar density and luminosity of galaxies gradually fall outward, the question of their size actually rests on the capabilities of the telescope, on its ability to distinguish the faint glow of the outer regions of the galaxy against the background of the glow of the night sky. Modern technology makes it possible to register regions of galaxies with a brightness less than 1% of the brightness of the sky; this is about a million times lower than the brightness of the nuclei of galaxies. According to this isophote (lines of equal brightness), the diameters of galaxies range from several thousand light-years in dwarf systems to hundreds of thousands in giant ones. As a rule, the diameters of galaxies correlate well with their absolute luminosity.

Spectral class and color. The first spectrogram of the galaxy - the Andromeda Nebulae, obtained at the Potsdam Observatory in 1899 by J. Scheiner (1858–1913), resembles the spectrum of the Sun with its absorption lines. The mass study of the spectra of galaxies began with the creation of "fast" spectrographs with low dispersion (200–400 /mm); Later, the use of electronic image intensifiers made it possible to increase the dispersion to 20–100/mm. Morgan's observations at the Yerkes Observatory showed that, despite the complex stellar composition of galaxies, their spectra are usually close to the spectra of stars of a certain class from A before K, and there is a noticeable correlation between the spectrum and the morphological type of the galaxy. As a rule, the class spectrum A have irregular galaxies Im and spirals sm And SD. class spectra A–F at the spirals SD And sc. Transfer from sc To Sb accompanied by a change in the spectrum from F To F–G, and the spirals Sb And Sa, lenticular and elliptic systems have spectra G And K. True, later it turned out that the radiation of galaxies of the spectral type A actually consists of a mixture of light from giant stars of spectral classes B And K.

In addition to absorption lines, many galaxies show emission lines, like the emission nebulae of the Milky Way. Usually these are hydrogen lines of the Balmer series, for example, H  on  6563, doublets of ionized nitrogen (N II) on  6548 and 6583 and sulfur (S II) on  6717 and 6731, ionized oxygen (O II) on  3726 and 3729 and doubly ionized oxygen (O III) on  4959 and 5007. The intensity of the emission lines usually correlates with the amount of gas and supergiant stars in the disks of galaxies: these lines are absent or very weak in elliptical and lenticular galaxies, but increase in spiral and irregular ones - from Sa To Im. In addition, the intensity of the emission lines of elements heavier than hydrogen (N, O, S) and, probably, the relative abundance of these elements decrease from the core to the periphery of disk galaxies. Some galaxies have unusually strong emission lines in their cores. In 1943, K. Seifert discovered a special type of galaxies with very broad lines of hydrogen in their nuclei, indicating their high activity. The luminosity of these nuclei and their spectra change with time. In general, the nuclei of Seyfert galaxies are similar to quasars, although not as powerful.

Along the morphological sequence of galaxies, the integral index of their color changes ( B-V), i.e. the difference between the magnitude of a galaxy in blue B and yellow V rays. Average The colors of the main types of galaxies are as follows:

On this scale, 0.0 corresponds to white color, 0.5 - yellowish, 1.0 - reddish.

With detailed photometry, it usually turns out that the color of the galaxy changes from the core to the edge, which indicates a change in the stellar composition. Most galaxies are bluer in the outer regions than in the core; this is much more noticeable in spirals than in ellipticals, since their disks contain many young blue stars. Irregular galaxies, usually devoid of a nucleus, are often in dove center than on the edge.

Rotation and mass. The rotation of the galaxy around an axis passing through the center leads to a change in the wavelength of the lines in its spectrum: the lines from the regions of the galaxy approaching us are shifted to the violet part of the spectrum, and from the receding regions - to the red (Fig. 7). According to the Doppler formula, the relative change in the wavelength of the line is   / = V r /c, Where c is the speed of light, and V r is the radial velocity, i.e. source velocity component along the line of sight. The periods of revolution of stars around the centers of galaxies are hundreds of millions of years, and the speeds of their orbital motion reach 300 km/s. Usually the disk rotation speed reaches its maximum value ( V M) at some distance from the center ( r M), and then decreases (Fig. 8). Our Galaxy V M= 230 km/s at distance r M= 40 thousand St. years from the center:

Rice. 7. SPECTRAL LINES OF THE GALAXY, rotating around the axis N, when the spectrograph slit is oriented along the axis ab. A line from the receding edge of the galaxy ( b) is deflected to the red side (R), and from the approaching edge ( a) to ultraviolet (UV).

Rice. 8. GALAXY ROTATION CURVE. Rotational speed V r reaches its maximum value V M in the distance R M from the center of the galaxy and then slowly decreases.

The absorption lines and emission lines in the spectra of galaxies have the same shape, therefore, stars and gas in the disk rotate at the same speed in the same direction. When, by the location of dark dust lanes in the disk, it is possible to understand which edge of the galaxy is closer to us, we can find out the direction of twisting of the spiral arms: in all the studied galaxies they are lagging behind, i.e., moving away from the center, the arm bends in the direction opposite to the direction rotation.

An analysis of the rotation curve makes it possible to determine the mass of the galaxy. In the simplest case, equating the gravitational force to the centrifugal force, we obtain the mass of the galaxy inside the star's orbit: M = rV r 2 /G, Where G is the gravitational constant. An analysis of the motion of peripheral stars makes it possible to estimate the total mass. Our Galaxy has a mass of approx. 210 11 solar masses, for the Andromeda Nebula 410 11 , for the Large Magellanic Cloud - 1510 9 . The masses of disk galaxies are approximately proportional to their luminosity ( L), so the ratio M/L they have almost the same and for the luminosity in blue rays is equal M/L 5 in units of mass and luminosity of the Sun.

The mass of a spheroidal galaxy can be estimated in the same way, taking instead of the disk rotation speed the speed of the chaotic motion of stars in the galaxy (  v), which is measured by the width of the spectral lines and is called the velocity dispersion: M  R v 2 /G, Where R is the galaxy radius (virial theorem). The velocity dispersion of stars in elliptical galaxies is usually from 50 to 300 km/s, and the masses are from 10 9 solar masses in dwarf systems to 10 12 in giant ones.

radio emission The Milky Way was discovered by K. Jansky in 1931. The first radio map of the Milky Way was received by G. Reber in 1945. This radiation comes in a wide range of wavelengths  or frequencies  = c/ , from several megahertz (   100 m) up to tens of gigahertz (   1 cm), and is called "continuous". Several physical processes are responsible for it, the most important of which is the synchrotron radiation of interstellar electrons moving almost at the speed of light in a weak interstellar magnetic field. In 1950, continuous radiation at a wavelength of 1.9 m was discovered by R. Brown and C. Hazard (Jodrell Bank, England) from the Andromeda Nebula, and then from many other galaxies. Normal galaxies, like ours or M 31, are weak sources of radio waves. They radiate in the radio range hardly one millionth of their optical power. But in some unusual galaxies, this radiation is much stronger. The nearest "radio galaxies" Virgo A (M 87), Centaur A (NGC 5128) and Perseus A (NGC 1275) have a radio luminosity of 10–4 10–3 of the optical one. And for rare objects, such as the Cygnus A radio galaxy, this ratio is close to unity. Only a few years after the discovery of this powerful radio source, it was possible to find a faint galaxy associated with it. Many weak radio sources, probably associated with distant galaxies, have not yet been identified with optical objects.

Astronomy is an amazingly fascinating science that reveals to inquisitive minds all the diversity of the Universe. There are hardly any people who, in their childhood, would never have watched a scattering of stars in the night sky. This picture looks especially beautiful in summer period when the stars seem so close and incredibly bright. IN last years Astronomers around the world are particularly interested in Andromeda, the galaxy closest to our own Milky Way. We decided to find out what exactly attracts scientists in it and whether it can be seen with the naked eye.

Andromeda: a brief description

The Andromeda Nebula, or simply Andromeda, is one of the largest galaxy in the galaxy. It is larger than our Milky Way, where the solar system is located, approximately three to four times. In it, according to preliminary estimates, about one trillion stars.

Andromeda is a spiral galaxy, it can be seen in the night sky even without special optical devices. But keep in mind that the light from this star cluster travels to our Earth for more than two and a half million years! Astronomers say that we now see the Andromeda Nebula as it was two million years ago. Isn't that a miracle?

Andromeda Nebula: from the history of observations

Andromeda was first seen by an astronomer from Persia. He cataloged it in 1946 and described it as a hazy glow. Seven centuries later, the galaxy was described by a German astronomer who observed it for a long time with a telescope.

In the middle of the nineteenth century, astronomers determined that the spectrum of Andromeda differed significantly from previously known galaxies, and suggested that it was composed of many stars. This theory is fully justified.

The Andromeda Galaxy, which was photographed only at the end of the nineteenth century, has a spiral structure. Although in those days it was considered only a large part of the Milky Way.

The structure of the galaxy

With the help of modern telescopes, astronomers have managed to analyze the structure of the Andromeda Nebula. The Hubble telescope made it possible to see about four hundred young stars revolving around the black hole. This star cluster is approximately 200 million years old. This structure of the galaxy was very surprising to scientists, because until now they had not even imagined that stars could form around a black hole. According to all previously known laws, the process of condensing gas to form a star out of it is simply impossible under the conditions of a black hole.

The Andromeda Nebula has several satellite dwarf galaxies, they are located on its outskirts and could be there as a result of absorption. This is doubly interesting given that astronomers are predicting a collision between the Milky Way and the Andromeda Galaxy. True, this phenomenal event will happen very soon.

The Andromeda Galaxy and the Milky Way: moving towards each other

Scientists have long been making certain predictions by observing the movement of both star systems. The fact is that Andromeda is a galaxy that is constantly moving towards the Sun. At the beginning of the twentieth century, an American astronomer was able to calculate the speed at which this movement occurs. This figure, which is three hundred kilometers per second, is still used by all astronomers in the world in their observations and calculations.

However, their calculations differ significantly. Some scientists claim that the galaxies will collide only after seven billion years, while others are sure that the speed of Andromeda is constantly growing, and the meeting can be expected in four billion years. Scientists do not exclude such a scenario in which in a few decades this predicted figure will again significantly decrease. At the moment, however, it is generally accepted that collisions should not be expected earlier than in four billion years. What threatens us Andromeda (galaxy)?

Collision: what will happen?

Since the absorption of the Milky Way by Andromeda is inevitable, astronomers are trying to simulate the situation in order to have at least some information about this process. According to computer data, as a result of absorption, the solar system will be on the outskirts of the galaxy, it will fly over a distance of one hundred and sixty thousand light years. Compared to the current position of our solar system towards the center of the galaxy, it will move away from it by twenty-six thousand light-years.

The new future galaxy has already received the name - Milky Honey, and astronomers say that due to the merger, it will rejuvenate by at least one and a half billion years. In this process, new stars will be formed, which will make our galaxy much brighter and more beautiful. She will also change shape. Now the Andromeda Nebula is at some angle to the Milky Way, but in the process of merging the resulting system will take on the shape of an ellipse and become more voluminous, so to speak.

The fate of mankind: will we survive the collision?

And what will happen to people? How will the meeting of galaxies affect our Earth? Surprisingly, scientists say that absolutely nothing! All changes will be expressed in the appearance of new stars and constellations. The sky map will change completely, because we will find ourselves in a completely new and unexplored corner of the galaxy.

Of course, some astronomers leave an extremely small percentage of negative developments. In this scenario, the Earth could collide with the Sun or another stellar body from the Andromeda galaxy.

Are there planets in the Andromeda Nebula?

Scientists regularly search for planets in galaxies. They do not leave attempts to find in the expanses of the Milky Way a planet that is close in characteristics to our Earth. At the moment, more than three hundred objects have already been discovered and described, but they are all located in our star system. In recent years, astronomers have begun to look more and more closely at Andromeda. Are there any planets out there?

Thirteen years ago, a group of astronomers using latest method hypothesized that one of the stars of the Andromeda Nebula has a planet. Its estimated mass is six percent of the largest planet in our solar system - Jupiter. Its mass is three hundred times the mass of the Earth.

At the moment, this assumption is being tested, but it has every chance of becoming a sensation. After all, until now, astronomers have not discovered planets in other galaxies.

Preparing to search for a galaxy in the sky

As we have said, even with the naked eye you can see the neighboring galaxy in the night sky. Of course, for this you need to have some knowledge in the field of astronomy (at least know what the constellations look like and be able to find them).

In addition, it is almost impossible to see certain clusters of stars in the night sky of the city - light pollution will prevent observers from seeing at least something. Therefore, if you still want to see the Andromeda Nebula with your own eyes, then go to the village at the end of summer, or at least to the city park, where there are not a lot of lanterns. best time for observation is October, but from August to September it is quite clearly visible above the horizon.

Andromeda Nebula: search scheme

Many young amateur astronomers dream of knowing what Andromeda really looks like. The galaxy in the sky resembles a small bright spot, but you can find it thanks to bright stars that are located nearby.

The easiest way is to find Cassiopeia in the autumn sky - it looks like the letter W, only more stretched than it is customary to designate it in writing. Usually the constellation is clearly visible in the Northern Hemisphere and is located in the eastern part of the sky. The Andromeda Galaxy lies below. To see it, you need to find a few more landmarks.

They are three bright stars below Cassiopeia, they are elongated in a line and have a red-orange hue. The middle one, Miraak, is the most accurate guide for beginner astronomers. If you draw a straight line upwards from it, you will notice a small luminous spot resembling a cloud. It is this light that will be the Andromeda galaxy. Moreover, the glow that you can observe was sent to the Earth even when there was not a single person on the planet. Amazing Fact, is not it?

Big Encyclopedic Dictionary

Extragalactic nebulae or island universes, giant star systems that also contain interstellar gas and dust. The solar system is part of our Milky Way Galaxy. All outer space to the limits where they can penetrate ... ... Collier Encyclopedia

Giant (up to hundreds of billions of stars) star systems; these include, in particular, our Galaxy. Galaxies are divided into elliptical (E), spiral (S) and irregular (Ir). The nearest galaxies to us are the Magellanic Clouds (Ir) and the nebula ... ... encyclopedic Dictionary

Giant stellar systems similar to our stellar system, the Galaxy (See Galaxy), which includes the Solar System. (The term "galaxies", in contrast to the term "Galaxy", is written with a lowercase letter.) Obsolete name G. ... ...

Giant (up to hundreds of billions of stars) star systems; these include, in particular, our Galaxy. Galaxies are divided into elliptical (E), spiral (S) and irregular (Ir). The nearest galaxies to us are the Magellanic Clouds (Ir) and the nebula ... ... Astronomical dictionary

galaxies- giant star systems with the number of stars from tens to hundreds of billions in each. Contemporary estimates give about 150 million galaxies in the known Metagalaxy. Galaxies are divided into elliptical (indicated in astronomy by the letter E), ... ... Beginnings of modern natural science

Giant (up to hundreds of billions of stars) star systems; these include, in particular, our Galaxy. G. are subdivided into elliptical. (E), spiral (S) and irregular (Ir). The closest to us G. Magellanic Clouds (Ir) and the Andromeda Nebula (S). G.… … Natural science. encyclopedic Dictionary

The Whirlpool Galaxy (M51) and its satellite NGC 5195. Photograph from the Kitt Peak Observatory. Interacting galaxies galaxies close enough in space that mutual gravity is significant in ... Wikipedia

Star systems that differ in shape from spiral and elliptical systems by randomness, raggedness. Sometimes there are N. g., which do not have a clear form, amorphous. They consist of stars with an admixture of dust, while most N. g. ... ... Great Soviet Encyclopedia

- ... Wikipedia

Books

• Galaxies, Avedisova Veta Sergeevna, Surdin Vladimir Georgievich, Vibe Dmitry Zigfridovich. The fourth book in the series "Astronomy and Astrophysics" contains an overview of modern ideas about giant star systems - galaxies. It is told about the history of the discovery of galaxies, about their ...
• Galaxies, Surdin VG. The fourth book from the series "Astronomy and Astrophysics" contains an overview of modern ideas about giant star systems - galaxies. It is told about the history of the discovery of galaxies, about their ...

Understanding how and when galaxies, stars and planets could appear, scientists have come close to unraveling one of the main mysteries of the Universe. they claim that as a result big bang- and, as we already know, it happened 15-20 billion years ago (see "Science and Life" No.) - exactly such material arose from which they could subsequently form celestial bodies and their collections.

Planetary gas nebula Ring in the constellation Lyra.

The Crab Nebula in the constellation Taurus.

The Great Nebula of Orion.

The Pleiades star cluster in the constellation Taurus.

The Andromeda Nebula is one of the closest neighbors of our galaxy.

Satellites of our Galaxy are galactic clusters of stars: Small (above) and Large Magellanic Clouds.

An elliptical galaxy in the constellation Centaurus with a broad dust lane. It is sometimes called Cigar.

One of the largest spiral galaxies, visible from Earth through powerful telescopes.

Science and life // Illustrations

Our Galaxy - the Milky Way - has billions of stars, and they all move around its center. In this huge galactic carousel, not only stars are spinning. There are also foggy spots, or nebulae. There aren't many of them visible to the naked eye. Another thing, if we consider starry sky through binoculars or a telescope. What kind of cosmic fog will we see? Distant small groups of stars that cannot be seen individually, or something completely, completely different?

Today, astronomers know what a particular nebula is. It turned out that they are completely different. There are nebulae that are made of gas and are illuminated by stars. Often they are round in shape, for which they are called planetary. Many of these nebulae were formed as a result of the evolution of aged massive stars. An example of the "foggy remnant" of a supernova (we'll tell you more about what it is) is the Crab Nebula in the constellation Taurus. This crab-like nebula is quite young. It is known that she was born in 1054. There are nebulae and much older, their age is tens and hundreds of thousands of years.

Planetary nebulae and remnants of once erupted supernovae might be called monument nebulae. But other nebulae are also known, in which stars do not go out, but, on the contrary, are born and grow up. Such, for example, is the nebula that is visible in the constellation of Orion, it is called the Great Nebula of Orion.

Nebulae, which are clusters of stars, turned out to be completely different from them. The Pleiades cluster is clearly visible to the naked eye in the constellation Taurus. Looking at it, it is hard to imagine that this is not a cloud of gas, but hundreds and thousands of stars. There are also more “rich” clusters of hundreds of thousands or even millions of stars! Such stellar "balls" are called globular star clusters. A whole retinue of such "balls" surrounds the Milky Way.

Most of the star clusters and nebulae visible from the Earth, although they are located at very large distances from us, still belong to our Galaxy. Meanwhile, there are very distant foggy spots, which turned out to be not star clusters, not nebulae, but entire galaxies!

Our most famous galactic neighbor is the Andromeda Nebula in the constellation Andromeda. When viewed with the naked eye, it looks like a hazy patch. And in photographs taken with large telescopes, the Andromeda Nebula appears as a beautiful galaxy. Through a telescope, we see not only many of its constituent stars, but also stellar branches emerging from the center, which are called “spirals” or “sleeves”. In size, our neighbor is even larger than the Milky Way, its diameter is about 130 thousand light years.

The Andromeda Nebula is the closest spiral galaxy to us and the largest known spiral galaxy. A beam of light goes from it to the Earth "only" about two million light years. So, if we wanted to greet the "Andromedans" by signaling them with a bright spotlight, they would know about our efforts in almost two million years! And the answer from them would have come to us after the same time, that is, back and forth - about four million years. This example helps to imagine how far the Andromeda Nebula is from our planet.

In the photographs of the Andromeda Nebula, not only the galaxy itself, but also some of its satellites are clearly visible. Of course, the satellites of the galaxy are not at all the same as, for example, planets - satellites of the Sun or the Moon - a satellite of the Earth. Satellites of galaxies are also galaxies, only "small", consisting of millions of stars.

There are satellites in our galaxy. There are several dozen of them, and two of them are visible to the naked eye in the sky of the Southern Hemisphere of the Earth. Europeans first saw them during the circumnavigation of Magellan. They thought they were some kind of clouds and named them the Large Magellanic Cloud and the Small Magellanic Cloud.

The satellites of our Galaxy are, of course, closer to Earth than the Andromeda Nebula. Light from the Large Magellanic Cloud takes only 170,000 years to reach us. Until recently, this galaxy was considered the closest satellite of the Milky Way. But recently, astronomers have discovered satellites and closer, however, they are much smaller than the Magellanic Clouds, and are not visible to the naked eye.

Examining the "portraits" of some galaxies, astronomers found that among them there are dissimilar to the Milky Way in structure and shape. There are also many such galaxies - these are both beautiful galaxies and completely shapeless galaxies, similar, for example, to the Magellanic Clouds.

Less than a hundred years have passed since astronomers made an amazing discovery: distant galaxies scatter one from the other in all directions. To understand how this happens, you can use balloon and do the simplest experiment with it.

Use ink, felt-tip pen or paint to draw small circles or squiggles to represent galaxies on the balloon. When you start to inflate the balloon, the drawn "galaxies" will diverge farther and farther from one another. This is what happens in the universe.

Galaxies rush, stars are born, live and die in them. And not only stars, but also planets, because there are probably many star systems in the Universe that are similar and unlike ours. solar system born in our galaxy. Recently, astronomers have already discovered about 300 planets moving around other stars.