The galaxies. Types of galaxies in the universe
Many facts, known today, seem sofamiliar and familiar, that it is difficult to imagine how they used to live without them. However, scientific truths in the majority arose not at the dawn of mankind. In many respects this concerns knowledge about outer space. Types of nebulae, galaxies, stars are known to almost everyone today. Meanwhile, the path to a modern understanding of the structure of the universe was quite long. People did not immediately realize that the planet is part of the solar system, and it is the Galaxy. Types of galaxies began to be studied in astronomy even later, when it became understood that the Milky Way is not alone and the universe is not limited to them. The founder of classification, as well as general knowledge of the cosmos beyond the "milk road", was Edwin Hubble. Thanks to his research today, we know a lot about galaxies.
Types of galaxies in the universe
Hubble studied nebulae and proved that many of thethey are similar to the Milky Way. Based on the collected material, he described what kind of galaxy is and what types of similar space objects exist. Hubble measured distances to some of them and offered his classification. Scientists are using it today.
The entire set of systems in the universe he divided into 3 types: galaxies elliptical, spiral and irregular. Each type is actively studied by astronomers around the world.
A piece of the universe, where the Earth is located, the Milky Way, refers to the type of "spiral galaxies". The types of galaxies are distinguished on the basis of the differences in their forms that affect certain properties of objects.
Spiral-shaped
Types of galaxies are common in the universethe same. According to modern data, spirals are more common than others. In addition to the Milky Way, this type includes the Andromeda Nebula (M31) and the galaxy in the constellation Triangle (M33). Such objects have an easily recognizable structure. If you look from the side, what a galaxy looks like, the top view will resemble concentric circles that diverge along the water. From the spherical central bulge, called bulge, spiral arms diverge. The number of such branches varies from 2 to 10. The entire disk with spiral arms is inside a dilute cloud of stars, which in astronomy is called "halo." The core of the galaxy is a cluster of stars.
Subtypes
In astronomy, for the designation of spiral galaxies, the letter S is used. They are divided into types depending on the structural design of the arms and features of the general form:
Galaxy Sa: sleeves tightly twisted, smooth and unformed, bulge bright and extended;
galaxy Sb: sleeves are powerful, clear, bulge less pronounced;
galaxy Sc: the sleeves are well developed, they are a tiny structure, the bulge is seen badly.
In addition, some spiral systems have a central almost straight jumper (it is called a "bar"). In this case, the letter B (Sba or Sbc) is added to the designation of the galaxy.
Formation
The formation of spiral galaxies, judging byeverything, it is similar to occurrence of waves from impact of a stone on a surface of water. The emergence of sleeves, according to scientists, led to some impetus. The spiral arms themselves are waves of increased density of matter. The nature of the shock can be different, one of the options is moving in the central mass of the stars.
Spiral branches are young stars andneutral gas (the main element is hydrogen). They lie in the plane of rotation of the galaxy, because it looks like a flattened disk. The formation of young stars is also possible in the center of such systems.
Nearest neighbor
The Andromeda Nebula is a spiral galaxy: The top view of it reveals several hoses that emanate from the common center. From the Earth with the naked eye, you can see it as a fuzzy blurry spot. In size, the neighbor of our galaxy is slightly larger than her: 130,000 light years in diameter.
The Andromeda nebula, although closest toThe Milky Way galaxy, and the distance to it is huge. Light in order to overcome it, it takes two million years. This fact perfectly explains why flights to the neighboring galaxy are still possible only in fantastic books and films.
Elliptical Systems
Let us now consider other types of galaxies. The photo of the elliptical system clearly demonstrates its difference from the spiral counterpart. Such a galaxy does not have sleeves. It looks like an ellipse. Such systems can be compressed to different degrees, to be something like a lens or a ball. In such galaxies, there is practically no cold gas. The most impressive representatives of this type are filled with rarefied hot gas, the temperature of which reaches a million degrees or more.
A distinctive feature of many elliptical galaxies- a reddish hue. For a long time, astronomers believed this to be a sign of the antiquity of such systems. It was believed that they mainly consist of old stars. However, studies of recent decades have shown the fallacy of this assumption.
Education
For a long time there was another hypothesis,connected with elliptical galaxies. They were considered the very first of the emerged, formed soon after the Big Bang. Today this theory is considered obsolete. A great contribution to its refutation was made by German astronomers Alar and Yuri Tumre, as well as the American scientist Francois Schweitzer. Their studies and discoveries of recent years confirm the validity of another hypothesis, a hierarchical model of development. According to it, larger structures were formed from fairly small ones, that is, galaxies did not form immediately. Their appearance was preceded by the formation of star clusters.
Elliptical systems with modernrepresentations were formed from spirals as a result of the fusion of sleeves. One of the confirmations of this is a large number of "twisted" galaxies, observed in remote areas of space. On the contrary, in the most approximate regions, the concentration of elliptic systems, bright enough and extended, is noticeably higher.
Symbols
Elliptical galaxies in astronomy alsoreceived their designations. For them, use the symbol "E" and the numbers from 0 to 6, which indicate the degree of flattening of the system. E0 are galaxies of practically regular spherical shape, and E6 are the flattest.
The surging cores
The elliptical galaxies include NGC systems5128 from the constellation Centaurus and M87, located in Virgo. Their feature is powerful radio emission. Astronomers are primarily interested in the structure of the central part of such galaxies. Observations of Russian scientists and the Hubble telescope show a fairly high activity of this zone. In 1999, American astronomers received data on the nucleus of the elliptical galaxy NGC 5128 (constellation Centaur). There in constant motion are huge masses of hot gas, twisting around the center, possibly a black hole. There is as yet no precise data on the nature of such processes.
Systems of irregular shape
The appearance of a galaxy of the third type is notstructured. Such systems are shredded objects of a chaotic form. Wrong galaxies are found on the outer space less often than others, but their study contributes to a more accurate understanding of the processes taking place in the universe. Up to 50% of the mass of such systems is gas. In astronomy, it is customary to designate similar galaxies through the symbol Ir.
Satellites
To galaxies of irregular shape are twoThe systems closest to the Milky Way. These are his companions: The Big and Small Magellanic Cloud. They are clearly visible in the night sky of the southern hemisphere. The largest of the galaxies is located at a distance of 200,000 light-years from us, and the smaller is separated from the Milky Way by 170,000 light-years. years.
Astronomers carefully study the expanses of thesesystems. And the Magellanic Clouds fully repay for this: in galaxy-satellites, very interesting objects are often found. For example, on February 23, 1987, a supernova broke out in the Large Magellanic Cloud. The emission nebula of Tarantula is also of special interest.
Interaction
The main types of galaxies describe the featuresform and location of elements of these space systems. However, the question of their interaction is no less interesting. It's no secret that all objects of the cosmos are in constant motion. Not an exception and the galaxy. Types of galaxies, at least some of their representatives could have formed during the process of merging or collision of the two systems.
If we recall what theobjects, it becomes clear how large-scale changes occur during their interaction. A colossal amount of energy is released when a collision occurs. It is interesting that such events are even more probable on the expanses of space than the meeting of two stars.
However, the "communication" of galaxies does not always endcollision and explosion. A small system can pass through its large brother, while disturbing its structure. Thus, formations are formed, similar in appearance to elongated corridors. They consist of stars and gas and often become zones of the formation of new stars. Examples of such systems are well known to scientists. One of them - the galaxy Wheel of a cart in the constellation Sculptor.
In some cases, systems do not collide, butpass by each other or only slightly touch. However, regardless of the degree of interaction, it leads to serious changes in the structure of both galaxies.
Future
Under the assumptions of scientists, it is possible that throughsome, quite a long time, the Milky Way will swallow up its nearest companion, a relatively recently discovered tiny space system, located 50 light years away from us. The data from the studies indicate the impressive lifespan of this satellite, which is likely to end in the process of merging with its larger neighbor.
Clash is a possible future for the Milky Waypaths and the Andromeda Nebula. Now a huge neighbor separates about 2.9 million light years from us. Two galaxies approach each other at a speed of 300 km / s. Probable collision is calculated by scientists in three billion years. However, whether it will happen or the galaxies will only slightly touch each other, today exactly no one knows. For forecasting, there is insufficient data on the features of the movement of both objects.
Modern astronomy studies in detail suchspace structures, like galaxies: galaxy species, features of interaction, their differences and similarities, the future. In this area there is still a lot of incomprehensible and requiring additional study. The types of structure of galaxies are known, but there is no exact understanding of many details related, for example, to their formation. Modern rates of improvement of knowledge and technology, however, allow us to hope for significant breakthroughs in the future. In any case, the galaxies will not cease to be the center of many studies. And this is due not only to the curiosity inherent in all people. Data on cosmic laws and the life of stellar systems allow us to predict the future of our piece of the universe, the Milky Way galaxy.
