The gravity of the Local Group affects their movement in space, but their relationships are not limited to this.
Many of them exchange matter, and, as a rule, flows from smaller galaxies to larger ones. Such an exchange occurs between Magellanic and. The gas coming from the planet fuels the formation of new ones in the Milky Way.
Matter flows into our star system and from the galaxy into the Sculptor. This is a faint nebulous object that is visible in the southern night sky only at , although the galaxy itself is 6 times closer to us than
.
It looks like a large globular cluster and belongs to the class of dwarf spheroidal galaxies with a diameter about 50 times smaller than the Milky Way. There are no giant stars, of which there are many in the Magellanic Clouds, or nebulae.
Astronomers have no doubt that many more members of the Local Group remain undiscovered. This is hampered by the own radiation of the equatorial part of the Milky Way, which “overlaps” large areas of the sky.
Recently, another dwarf spheroidal galaxy was discovered in this area - it is located in the constellation Pegasus. It is possible that this “crumb” is also a satellite of spiral Andromeda, which dominates the Local Group.
The new galaxy hides behind the bright glow of the Milky Way and is a cluster of faint blue stars 2 thousand light years across.
Astronomers believe that dwarf galaxies are " building blocks", from which large star systems eventually form.
After the exact location in the Milky Way galaxy was established, astronomers were faced with the task of determining the place of our Galaxy itself in the hierarchy of the Universe.
First of all, it turned out that it is not part of any of the large clusters of galaxies, although the irregular cluster in the constellation Virgo, well known to astronomers, is located relatively nearby.
Further research confirmed that the Milky Way is part of a smaller structure called Local group galaxies.
The Local Group includes galaxies whose distance does not exceed 5 million light years; more than fifty of them have been discovered so far. At this distance they are clearly visible gravitational interactions between them, and their center of mass is on the line connecting the Milky Way and the Andromeda Galaxy.
It is well known that ours is not at rest - it moves around the Sun. moves around the center of the Milky Way. The Milky Way, in turn, moves in the Local Group of galaxies. And the Local Group itself is moving towards large cluster galaxies in the constellation Virgo.
Recently, researchers were able to measure the speed of the Local Group, and it turned out to be unusually high - approximately 600 km/s.
This result came as a complete surprise to astronomers and astrophysicists - there is still no explanation for such a rapid “fall” into the Virgo cluster.
Local Group of Galaxies
The MW subgroup has a linear size of about 140 kpc, and the radial velocity dispersion of galaxies in it is 68 km/s.
 |
| Subgroups of the Community Group |
The Andromeda nebula galaxy system, visible from the outside, is grouped around its main galaxy M31, containing the closest galaxies with high surface brightness M32 and M110, as well as fainter and more distant NGC147 and NGC185, very faint systems And I, And II, And III .
In the summer of 1998, two groups of observers(I.D. Karachentsev and V.E. Karachentseva; T. Armandroff, J. Davies and G. Jacoby) at least 3 more dwarf spheroidal galaxies were discovered - possibly distant members of the subgroup M31(one of these galaxies was discovered independently by both groups): Pegasus DEG (And VI), Cassiopea Dw and And V. The third largest galaxy in the Local Group, M33 (Triangulum), which may or may not be a distant gravitationally bound companion to M31, itself has a dwarf companion LGS 3.
Galaxies NGC3109, Antlia,Sextans A And Sextans B, apparently, form a separate subgroup with V r=+114+-12 km/s, which is located outside the so-called “zero Local Group distance” of 1.7 Mpc from the Local Group centroid (van den Bergh, 1999).
Other members cannot be assigned to any main subgroup and move completely isolated in the gravitational field of the members of giant groups. The substructures in the group are probably not stable. Observations and calculations suggest that the groups are very dynamic and have changed significantly in the past: the galaxies around the large elliptical galaxy Maffei 1 were likely once members of the group of our galaxy.
All of the above shows that the MG is not isolated, but is in gravitational interaction and exchange of members with the nearest surrounding groups of galaxies. Particularly noticeable is the interaction with:
| Galaxy | Alto. Name | RA (2000.0) | Dec (2000.0) | Type | V_r | Dist. | Diam. | V B tot | A B |
|---|---|---|---|---|---|---|---|---|---|
| WLM | DDO221 | 00:01:58 | -15:27:51 | IB(s)m IV-V | - 116 | 950 | 11.5x4.0 | 11.03 | 0.09 |
| IC 10 | UGC192 | 00:20:24 | +59:17:30 | IBM? | -344 | 660 | 6.3x5.1 | 11.80 | |
| Cetus | dSph | 775 | |||||||
| NGC 147 | DDO 3 | 00:33:12 | +48:30:29 | dE5 pec | -193 | 660 | 13.2x7.8 | 10.47 | 0.70 |
| And III | A0032+36 | 00:35:17 | +36:30:31 | dSph | 760 | 4.5x3.0 | 15.00 | 0.19 | |
| NGC 185 | UGC396 | 00:38:58 | +48:20:12 | dE3 pec + Sy | -202 | 620 | 11.7x10.0 | 10.10 | 0.78 |
| NGC205 | M 110 | 00:40:22 | +41:41:26 | E5 pec | - 241 | 725 | 21.9x11.0 | 8.92 | 0.14 |
| M32 | NGC 221 | 00:42:42 | +40:51:52 | E2 (cE2) | -205 | 725 | 8.7x6.5 | 9.03 | 0.31 |
| M31 | NGC 224 | 00:42:44 | +41:16:09 | SA(s)b Liner | -300 | 725 | 190x60 | 4.36 | 0.10 |
| And I | A0043+37 | 00:45:44 | +38:00:23 | dE3 pec ? | 810 | 2.5x2.5 | 13.6 | 0.20 | |
| SMC | NGC292 | 00:52:45 | -72:49:43 | SB(s)m pec | +158 | 58 | 320x185 | 2.7 | 0.17 |
| Scl dw Irr | E349-G31 | 00:08:13 | -34:34:42 | dIBm | +207 | 1.1x0.9 | 15.48 | ||
| Scl dSph | E351-G30 | 01:00:09 | -33:42:33 | dE3 pec | +110 | 84 | 39.8x30.9 | 10.50 | |
| LGS 3 | Psc dw | 01:03:53 | +21:53:05 | dIr/dSph | -277 | 810 | 2x2 | 18.00 | 0.10 |
| IC1613 | DDO 8 | 01:04:54 | +02:08:00 | IAB(s)m V | -234 | 720 | 16.2x14.5 | 9.88 | 0.02 |
| And V | 01:10:17 | +47:37:41 | dSph | 810 | |||||
| And II | 01:16:11 | +33:21:43 | E? | 680 | 3.6x2.52 | 13.5 | 0.14 | ||
| M33 | NGC 598 | 01:33:51 | +30:39:37 | SA(s)cd II-III | -179 | 795 | 70.8x41.7 | 6.27 | 0.18 |
| Phe dw | E245-G07 | 01:51:06 | -44:26:41 | IAm | +56 | 417 | 4.9x4.1 | 13.07 | |
| For dw | E356-G04 | 02:39:59 | -34:26:57 | dE4 | +53 | 140 | 17.0x12.6 | 9.04 | |
| LMC | E056-G115 | 05:23:34 | -69:45:22 | SB(s)m | +278 | 55 | 645x550 | 0.9 | 0.25 |
| Car dw | E206-G220 | 06:41:37 | -50:57:58 | dE3 | +229 | 100 | 23.4x15.5 | 22.14 | 0.10 |
| Leo A | DDO 69 | 09:59:24 | +30:44:42 | IBm V | +20 | 690 | 5.1x3.1 | 12.92 | 0.07 |
| Sex B | DDO 70 | 10:00:00 | +05:19:42 | Im+ IV-V | +301 | 1370 | 5.1x3.5 | 11.85 | 0.05 |
| NGC 3109 | DDO 236 | 10:03:07 | -26:09:32 | SB(s)m | +403 | 1260 | 19.1x3.7 | 10.39 | 0.14 |
| Antlia | A1001-27 | 10:01.8* | -27:05* | dE3 | +361 | 1320 | 1 | ||
| Leo I | Regulus G. | 10:08:27 | +12:18:27 | dE3 | +168 | 270 | 9.8x7.4 | 11.8 | 0.09 |
| Sex A | DDO 75 | 10:11:06 | -04:42:28 | IBm+ V | +324 | 1420 | 5.9x4.9 | 11.86 | 0.06 |
| Sex dw | 10:13:03 | -01:36:53 | dE3 | +230 | 87 | 0.07 | |||
| Leo II | DDO 93 | 11:13:29 | +22:09:17 | dE0 pec | +90 | 215 | 12.0x11.0 | 12.6 | 0.00 |
| GR 8 | DDO 155 | 12:58:39 | +14:13:02 | I'm V | +214 | 1700 | 1.1x1.0 | 14.68 | 0.04 |
| E269-G70 | 13:10.6* | -43:07* | -8 | ||||||
| IC 4247 | 13:24.0* | -30:06* | +274 | ||||||
| UMi dw | DDO 199 | 15:09:11 | +67:12:52 | dE4 | -209 | 60 | 30.2x19.1 | 11.9 | 0.04 |
| Dra dw | DDO 208 | 17:20:19 | +57:54:48 | dE0 pec | -281 | 76 | 35.5x24.4 | 10.9 | 0.08 |
| Milky Way | 17:45.6 | -28:56 | SAB(s)bc I-II ? | 0 | 10 | 30 | |||
| SagDEG | 18:55 | -30:30 | dE7 | 24 | |||||
Space is difficult arranged system, the elements of which are closely interconnected: planets unite around one star, stars form galaxies, and those form even larger associations, such as the Local Group of Galaxies. Multiplicity is a very common phenomenon in the Universe associated with high gravity. Thanks to it, a center of mass is formed around which both relatively small objects like stars and galaxies and their associations rotate.
The Local Group is believed to be based on three large objects: the Milky Way, the Andromeda Galaxy and the Triangulum Galaxy. By gravitational attraction their satellites are associated with them, as well as a number of dwarf galaxies, the belonging of which to one of the three systems cannot yet be established. In total, the Local Group of galaxies includes at least fifty large celestial objects, and with the improvement of the quality of technology for astronomical observations, this number is growing.
As already mentioned, multiplicity in is a common occurrence. The Local Group of galaxies is not the largest of these galaxies, although its size is impressive: it is about one megaparsec across (3.8 x 10 19 km). Along with other similar associations, the Local Group is included in the Virgo Supercluster. Its dimensions are difficult to imagine, but its mass has been measured relatively accurately: 2 × 10 45 kg. In total, this association includes about a hundred galactic systems.
It should be noted that the multiplicity does not end there. The Virgo Supercluster, like several others, form the so-called Laniakea. Studying such giant systems has allowed astrophysicists to create a theory of the large-scale structure of the Universe.
Scientists have found that the age of all members of the Local Group is approximately 13 billion years. In addition, the material that forms them has the same composition, which allows us to speak about the common origin of Local Group galaxies. They are not located in any random order: most of them are built around an imaginary line that runs between Milky Way and the Andromeda Nebula.
The largest member of the Local Group of galaxies by size is the Andromeda Nebula: its diameter is 260 thousand light years (2.5 × 10 18 km). In terms of mass, the Milky Way clearly stands out - approximately 6 × 10 42 kg. Along with such large objects, there are also dwarf objects like the SagDEG galaxy, located in the constellation Sagittarius.
Most of the Local Group galaxies are classified as irregular, but there are also spiral ones like the Andromeda Nebula and elliptical ones like the already mentioned SagDEG.
The accuracy of astronomical observations of the Local Group depends on what galaxy we are in. That is why the Milky Way is, on the one hand, the most studied object, and on the other hand, it causes greatest number questions. To date, it has been established that at least 14 objects are satellites of our galaxy, including the Ursa Major, Sagittarius, Sculptor and Leo galaxies.
Of particular note is the SagDEG galaxy in Sagittarius. It is the most distant from the gravitational center of the Local Group. According to calculations, the Earth is separated from this galaxy by 3.2 × 10 19 km.
One of the controversial issues is the connection between the Milky Way and the Magellanic Clouds - two galaxies so close to us that they can be observed with the naked eye from the Southern Hemisphere. For a long time it was believed that they were satellites of our galaxy. In 2006 when using latest technologies it was found that they move much faster than other satellites of the Milky Way. Based on this, it was suggested that they do not have a gravitational connection with our galaxy.
But it is indisputable further fate Magellanic Clouds. Their movement is directed towards the Milky Way, so their absorption by a larger galaxy is inevitable. According to scientists, this will happen after 4 billion years.
In 5 billion years, a similar fate threatens our galaxy, only Andromeda, the largest galaxy of the Local Group, poses a threat to it. The distance to is 2.5 × 10 6 light years. It has 18 satellites, of which, due to their brightness, the most famous are M23 and M110 (catalogue numbers from the 18th century French astronomer Charles Messier).
Although the Andromeda Nebula is the closest galaxy to Milky Way, observing it is greatly complicated due to its structure. It is one of the spiral galaxies: it has a pronounced center from which two large spiral arms emerge. However, the Andromeda Nebula is edge-on towards the Earth.
Its significant distance from the Earth significantly complicates the study of both the galaxy itself and its satellites. The number of satellites of the Triangulum Galaxy is controversial. For example, dwarf Andromeda II is located exactly in the middle between the Triangulum and the Nebula. The state of modern observation devices does not allow us to determine which of the two largest members of the Local Group of galaxies this gravitational field belongs to. Most still assume that Andromeda II is associated with Triangulum. But there are also representatives of the opposite point of view, who even propose to rename it Andromeda XXII.
The Triangulum Galaxy also contains one of the exotic objects in the Universe - the black hole M33 X-7, whose mass is 16 times that of the Sun, making it one of the largest known modern science black holes, excluding supermassive ones.
The number of members of the Local Group varies constantly, not only because of the discovery of other galaxies orbiting the same center of mass. Improvements in the quality of astronomical technology have made it possible to establish that objects previously considered galaxies are not actually galaxies.
This applies to a greater extent to balls. They contain a large number of stars tied to one gravitational center, and their shape resembles spherical galaxies. Quantitative relationships help to distinguish them: the density of stars in globular clusters is much higher, and the diameter is correspondingly higher. For comparison: in the vicinity of the Sun there is one star per 10 cubic parsecs, while in globular clusters this figure can be 700 and even 7000 times higher.
Palomar 12 in the constellation Capricorn and Palomar 4 in Ursa Major have long been considered dwarf galaxies. Recent studies have shown that they are in fact quite large globular clusters.
Until the second quarter of the 20th century, it was believed that the Milky Way and the Universe were identical concepts. All matter is supposedly located within our galaxy. However, in 1924, Edwin Hubble, using his telescope, recorded several Cepheids - variable stars with a pronounced period of luminosity - the distance to which clearly exceeded the size of the Milky Way. Thus, the existence of extragalactic objects was proven. Scientists have begun to think that the Universe is more complex than it previously seemed.
With his discovery, Hubble also proved that the Universe is expanding all the time, and objects are moving away from each other. Improvements in technology brought new discoveries. Thus, it was discovered that the Milky Way has its own satellites, the distances between them were calculated and the prospects for existence were determined. Such discoveries were enough to formulate for the first time the idea of the existence of the Local Group as an impressive association of closely related galaxies and even to suggest that associations of a higher rank may exist, since satellites were also discovered in the closest galaxy to the Milky Way - the Andromeda Nebula. The term “Local Group” itself was first used by the same Hubble. He mentions it in his work on measuring distances to other galaxies.
It can be argued that space exploration has just begun. This also applies to the Local Group. The SagDEG galaxy was discovered relatively recently, but the reason for this is not only its low luminosity, which was not detected by telescopes for a long time, but also the presence in the Universe of matter that does not have visible radiation - the so-called “dark matter”.
In addition, observations are complicated by diffuse interstellar gas (usually hydrogen) and cosmic dust. However, observational technology does not stand still, which allows us to count on new amazing discoveries in the future, as well as on clarifying existing information.
Local group of galaxies
The group of galaxies that includes our Milky Way is located on the periphery (at a distance of about 50 million light years from the center) of a giant cluster of galaxies visible in our sky in the constellation Virgo (Virgo Cluster) and consisting of more than 2000 star systems . It is formed at the intersection of two universal fibers of dark matter. It should be noted that this cluster is one of the great many superclusters of star islands that make up the fibrous megastructure of the part of the Universe observed today.
Hypothetical inhabitants of a highly developed civilization located in the center of the Virgo cluster, using powerful telescopes, could observe a close pair of spiral galaxies, indicated by faint hazy lines in the starry sky - this is how our Local Group is visible from there, the light from which would travel to these imaginary observers for 50 million years. About fifty smaller galaxies included in our group are difficult to register from such a huge distance, and conversely, the number of star systems included, according to modern calculations, in the Virgo Cluster does not include a huge number of dwarf galaxies. tick within this supercluster.
The concept of a Local Group used by astronomers can be interpreted as a small town on the outskirts of the country, on the streets of which its own laws apply. Its inhabitants actively interact, determining the present and future of each other, the stronger members of the community organize and subordinate to their will the movement of the weaker ones, and ultimately absorb them (scientists like to call these processes in the life of galaxies cannibalism), exciting in its expanded womb there are active processes of the birth of new generations of stars, planetary systems and, possibly, new organic life.
Similar scenarios describe the birth and development of our Galaxy and the Andromeda Galaxy (M31). The merger of this couple after several billion years is very likely from the point of view of modern science.
With a diameter of about 6 million light years, our Local Group represents the Universe in miniature. Its structure and composition allows us to study in detail the processes of birth, development and structure of all currently known types of galaxies. By studying the stars that form the galaxies in our immediate environment, using the most powerful ground-based and space telescopes, we obtain information about the age of the objects from which they consist. For the most ancient of them, it is 13 billion years old, which is almost equal to the age of the Universe. These are representatives of dwarf stars, in which nuclear combustion occurs extremely slowly. Oxygen, nitrogen, carbon, as well as heavier chemical elements(astrophysicists generally call them “metals”) were formed only during nuclear reactions in the depths of the stars. By shedding their shells or flaring up as Supernovae, the stars enriched the surrounding space with the products of their vital activity. Representatives of luminaries of later generations are much richer in heavy elements, and the younger the star, the greater its metallicity, the more recent generation it belongs to. Thus, determining the composition of the stellar population of members of the Local Group of galaxies allows us to draw a conclusion about the age of its members.
Astronomers have received a huge amount of statistical and factual material as a result of the implementation of the GOODS program (Great Observatori-es Origins Deep Survey, which in one of the literary translations sounds like this: “Deep study of the origin of objects of the Universe at the largest observatories”). At present, the most substantiated theory is that the first stars formed from cold dark matter, which makes up 90% of the baryonic matter of the Universe, or more precisely, from giant hydrogen clouds. star clusters and dwarf galaxies, which themselves had a very stormy, bright and explosive youth. Subsequently, from these dwarf galaxies, through their merger and mutual absorption by larger smaller ones, the spiral, elliptical, irregular galaxies that we observe today were formed.
Astronomers believe that our Local Group formed from a cloud of dark matter when the Universe cooled to a temperature of 2000 K, about 13 billion years ago. If we extrapolate the linear dimensions into the past, taking into account changes in the scale of the expanding Universe, then at that time the diameter of the group was 600,000 light years (a quarter of the current distance between the Milky Way and the Andromeda Nebula). Moreover, the sizes of the two largest galaxies should have been smaller, and the members of the Local Group should have been more numerous.
Local scale
In order to understand the scale relationships in our Local Group, Ray Willard, an employee of the Space Telescope Science Institute in Baltimore, proposed the following comparison in his article in the journal Astronomy. Let's imagine our Galaxy as a compact disc (diameter 12 cm), in the center of which a tennis ball is placed. Now imagine the same design, but 1.5 times larger. This will be the Andro-meda Nebula. By placing these two disks at a distance of 3 m, we obtain a model of a galactic pair, and all dwarf galaxies - satellites of our galaxies and more distant members of the group - will fit into a sphere with a radius of 4.5 m.
The oldest globular star clusters and dwarf galaxies collided and merged, forming the core of our Galaxy. In the process of further evolution, a disk with spiral arms was formed. The turbulent past has left behind traces that appear in the form of huge arc-shaped gas and stellar flows that exist in the galactic halo - a very rarefied stellar environment. The size of the Milky Way halo in the scale model adopted above would occupy the volume of a volleyball (according to other estimates, the diameter of a spherical halo is approximately equal to the diameter of the galactic disk).
Only a few of the relict globular clusters have survived to today. Within the Milky Way, they resemble the ruins of ancient castles. The ability to survive depended on their masses and trajectories relative to the disk of the “host” galaxy. Modern observations allow us to conclude that our Galaxy has absorbed, is absorbing and will continue to absorb smaller stellar communities. We wrote about the M12 cluster, which is in the process of destruction due to interaction with the galactic disk as it passes through its plane. Like the face of a child engrossed in eating jam, the face of our Galaxy bears many traces of large-scale meals. The galactic halo contains the remains of swallowed star systems, the disk of the Milky Way is deformed by the passages of satellites - dwarf galaxies. Streams of stars located along the previous trajectories of movement of dwarf satellites around the center of our Galaxy literally rain stars onto the galactic disk.
According to some assumptions, the huge star cloud in the Milky Way, which can be observed in the constellation Sagittarius, represents the “population” of a dwarf galaxy that merged with our stellar island in the distant past. According to Steve Majewski, an employee of the University of Virginia, this is the largest satellite of our Galaxy that ended up in its womb.
The most impressive trace of the Galaxy's turbulent past is the huge flows of cold hydrogen forming arcs spanning 100 arc degrees around the south galactic pole. At the head of these flows are the Large and Small Magellan clouds - the largest satellites of the Milky Way.
Mysteries of the Magellanic Clouds
The most recent studies of the movement of Magellanic clouds, carried out by astronomers Nithya Kallivavalil, Charles Alcock from the Harvard-Smithsonian Center for Astrophysics ( Nitya Kallivayalil, Charles Alcock, Harvard-Smithsonian Center for Astrophysics ) and Roland Van der Marel from the Space Telescope Science Institute ( Roeland van der Marel, Space Telescope Science Institute ), made it possible to clarify the dynamics of the motion of these dwarf galaxies. This dynamics was revised on the basis of refined values of the spatial velocity components of the Small and Large Magellanic Clouds.
The greatest difficulty was calculating the velocity component perpendicular to the line of sight. This required several years of meticulous observations (using the Hubble Space Telescope) and calculations. As a result, the authors presented surprising findings at the 209th Conference of the American Astronomical Society. It turned out that the LMC, relative to our Galaxy, has a speed of 378 km/s, while the SMC has a speed of 302 km/s. In both cases, the speeds “turned out to be significantly greater than previously expected. There can be two explanations for this fact:
The mass of the Milky Way is greater than previously thought. Magellanic clouds are not in orbit around the Galaxy and will overcome its gravitational forces in the future.
The difference in cloud speeds (i.e., the speed of their relative movement) is also surprisingly high. This suggests that they are not gravitationally connected to each other. In addition, this explains the fact that they have not merged with each other in the more than ten billion history of the Local Group. Detailed studies of hydrogen flows trailing in trails behind the Magellanic clouds are planned for the future. This will make it possible to clarify the trajectories of their movements relative to each other and relative to our Galaxy.
Laboratory in the backyard
The theory of the development and formation of galaxy clusters unsatisfactorily explains the possibility of the formation of an isolated pair of large galaxies on the periphery of a giant cluster in the constellation Virgo. Scientists consider it a gift from Fate to have such a wonderful representative of spiral galaxies in our immediate surroundings, which is M31, or the Andromeda Nebula. Moreover, nature decreed that the plane of its disk is under optimal angle towards the direction of an observer located on Earth (and on any planet located in our Galaxy). It is this angle of view that allows us to study with maximum care all the components - the core, spiral arms and halo of a huge stellar island.
Like our Galaxy, M31 contains many globular clusters. Some of them are located outside the spiral arms, but move around galactic centers without leaving the halo. The Hubble Space Telescope received an image of the globular star cluster G1, orbiting the center of M31 in an orbit with a radius of 130 thousand light years (the radius of the disk of the Andromeda Nebula is 70 thousand light years). G1, also designated Mayall II, is the brightest globular cluster in the Local Group: it consists of at least 300 thousand old stars. Analysis of this detailed image, obtained in the near infrared in July 1994, allows us to conclude that the cluster contains stars in which helium nuclear burning processes occur, and the temperature and brightness of these stars suggests that it is the same age as our Milky Way and the Local Group as a whole. G1 is unique in that it contains a 10,000 solar mass black hole at its center.
A real miracle is the MZZ, a spiral galaxy in the Triangulum (NGC 598, or Trian-gulum Pinwheel Galaxy). It is half the diameter of the Milky Way and three times the size of the Andromeda Nebula. According to astronomers, over billions of years of close coexistence with M31, it should have collided with it long ago. But for some still unclear reasons this did not happen.
The study of the Local Group - the Universe in miniature - allows scientists to penetrate into many of the secrets of the Universe.
There are black holes of various masses in our environment: in the center of our own Galaxy, in the center of the Andromeda Nebula and the globular clusters M15 and G1. The assumption that the mass of the central black hole should be one ten-thousandth of the mass of the entire galaxy is confirmed by the examples of the mentioned clusters. This makes it possible to identify some fundamental patterns connecting the parameters of black holes and their “mother” galaxies.
Of particular interest is the discovery of hypothetical compact massive non-luminous (invisible) baryonic halo objects that concentrate the light of more distant stars due to the effect of gravitational lensing.
Modern cosmological models, based on long-term observations of the starry sky and on the huge amount of factual material obtained, admit that planets similar to our Earth began to form more than ten billion years ago. Thus, the Universe developed a sufficient amount of time for the emergence of conditions that ensure the formation of high-molecular organic compounds and life, and also, given the colossal number of galaxies and stars, for the emergence of intelligence. No matter how improbable it may be, let us still assume that in our local group, besides us, there is only one highly developed civilization. It is natural to assume that its representatives are interested in the world around them. We can hope that their scientists, having a longer history behind them, have observed the evolution of our group of galaxies, and terrestrial science will eventually be able to obtain this knowledge. Our civilization happened to exist in a relatively calm period of galactic history, which will end in about 2-3 billion years with a grandiose cataclysm - the collision of the Milky Way and the Andromeda Nebula.
True, one important circumstance should be taken into account here. Our Galaxy and M31 are approaching at a speed of 120 km/s, or 3.8 billion km per year, or 400 light years in one billion years (as the distances between their centers decrease, this speed will increase). The radial velocity can be determined quite accurately from the shift of the spectral lines. However, does the velocity vector of relative motion have a tangential component? If it does, and it is large enough, then the collision will not occur at all, at least within the next tens of billions of years. Galaxies will pass each other at enormous speeds, stir up their “hairs” by mutual gravitational influences and continue traveling along elliptical trajectories, closing the colossal arcs of their orbits around general center wt.
It is still possible that the Milky Way and the Andromeda Nebula are on collision courses. It was this assumption that Thomas Cox and Avi Loeb from the Harvard-Smithsonian Center for Astrophysics (TJ. Cox, Avi Loeb, Harvard Smithsonian Center for Astrophysics) based their model on. Having carried out scrupulous calculations, introducing into the equations all currently known parameters and initial conditions, scientists concluded that our star will live until the time when galaxies begin to merge. According to researchers, the first "contact"will take place in 2 billion years. Terrestrial astronomers will observe increasing deformations of the spiral structures of our Galaxy under the influence of gravity of the approaching “stellar monster”. As a result of several oscillatory movements, indicated by the nuclei of galaxies, the population of their stellar disks will increasingly mix, gradually forming a relatively homogeneous body of a giant elliptical galaxy. According to the assumptions of Cox and Loeb, our star, in its extreme old age, will still reach the period of formation of the “final” structure and, if this can console anyone living today, will end up on the periphery of the newly formed stellar island at a distance of 100 thousand light years from its center. Whether this area will be a “life zone” of a new galaxy, in which dynamic and energy parameters will provide conditions favorable for the existence of life on the planets around the stars inhabiting it, is, of course, impossible to say today. Let's hope for the best, for the benefit of our descendants.
As Avi Loeb joked, observing all these enchanting and grandiose changes in the starry sky, future scientists may refer to the lines of his report: “This is my first publication that will be quoted 5 billion years later.”
Computer simulation of the merger of galaxies allows us to trace the development of events: at the first stage of the collision, processes similar to those observed today in the “Mouse” galaxy (NGC 4676) will occur. First, the Milky Way and M31 will come into contact with their peripheral regions. In the process of further, deeper mutual absorption, the pattern will resemble the Antennae galaxies (NGC 4038-4039). Then the nuclei will merge, then perhaps the black holes that exist at the center of each star system will collide. Then jets will appear - ejections of matter into intergalactic space, similar to those observed near the galaxy NGC 5128. The universal catastrophe will most likely end with the formation of one giant elliptical galaxy - an analogue of NGC 1316." All on- Our local group will submit to the gravitational influence of this galaxy, and the appetites of the newly baked monster will be so great that the remaining members of the group will be absorbed by it in a relatively short time (by galactic standards).
Let's not forget that the Local Group, among other things, is moving towards the center of the Virgo cluster at a speed of 3 million light years for every billion years. How would we avoid colliding with something larger (as they say, “don’t hit a pine tree”)... After all, there are clearly more invisible objects hidden from us in the Universe than there are directly observed! How many years has earthly science been collecting photographic data about the world of galaxies around us? About a hundred? In any case, this is not even a moment, it is just a frozen photograph of the Cosmos. The development of processes within such short periods of time is noticeable only within very small volumes of space. Besides evolution solar system, we can observe the expansion of the shells of novae, supernovae, changes in the interiors of gas and dust clouds under the influence of “hurricane winds” generated by the young stellar inhabitants of these regions of space. To understand the dynamics of such formations as a cluster of galaxies (even if “local” and on the “outskirts” of the solid Virgo cluster) requires at least millennia. Of course, over these millennia we plan to inform our readers about current changes in the surrounding Universe. There must be at least something stable in this world!
