The galaxies. Types of galaxies in the universe

Many facts, known today, seem so familiar 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. The 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 came to understand 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 the nebulae and proved that many of them are formations similar to the Milky Way. Based on the collected material, he described what kind of galaxy is and what types of such cosmic objects exist. Hubble measured distances to some of them and offered his classification. Scientists use it today.

All the 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 "spiraling galaxies". Types of galaxies are distinguished on the basis of differences in their forms that affect certain properties of objects.

Spiral-shaped

The types of galaxies are not the same throughout the universe. 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 the bulge, the spiral arms diverge. The number of such branches varies from 2 to 10. The entire disk with spiral arms is located inside a rarefied cloud of stars, which in astronomy is called "halo". The core of the galaxy is a cluster of stars.

Subtypes

In astronomy, the letter S is used to denote spiraling galaxies. They are divided into types depending on the structural design of the sleeves and the 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, represent a tattered 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, apparently, is similar to the appearance of waves from the impact of a stone on the surface of the 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 and neutral 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 possible in the center of such systems.

Nearest neighbor

The Andromeda Nebula is a spiral-shaped galaxy: the top view of it reveals several sleeves emanating from a 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.

Nebula Andromeda, although the closest to the 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 shows well 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 is a reddish shade. 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 related to elliptical galaxies. They were considered the very first of the emerged, formed soon after the Big Bang. Today, this theory is considered obsolete. A major contribution to its refutation was made by German astronomers Alar and Yuri Tumre, as well as the American scientist François Schweitzer. Their studies and discoveries in 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 according to modern concepts were formed from spirals as a result of 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

The elliptical galaxies in astronomy also received 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 5128 systems from the constellation Centaurus and M87, located in Virgo. Their feature is powerful radio emission. Astronomers are primarily interested in the arrangement 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 exact data on the nature of such processes.

Systems of irregular shape

The appearance of the third type of galaxy is not structured. Such systems are shredded objects of a chaotic form. Wrong galaxies are found in space more rarely 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 such galaxies through the symbol Ir.

Satellites

To galaxies of irregular shape are two systems, most closely located to the Milky Way. They 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 thousand light-years from us, and the smaller is separated from the Milky Way - 170,000 light years. years.

Astronomers carefully study the expanses of these systems. And the Magellanic Clouds fully repay for this: in galaxy-satellites are often found very interesting objects. For example, on February 23, 1987, a supernova broke out in the Large Magellanic Cloud. The emission nebula Tarantula is also of special interest. It is also located in the Large Magellanic Cloud. Here scientists have discovered a region of constant star formation. Some of the stars that make up the nebula are only two million years old. In addition, here is the most impressive of the stars found in 2011 - RMC 136a1. Its mass is 256 solar.

Interaction

The main types of galaxies describe the features of the shape and arrangement of the elements of these cosmic 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. The types of galaxies, at least some of their representatives, could have formed during the fusion or collision of two systems.

If we recall what these objects are, it becomes clear how large-scale changes occur during their interaction. In the collision a huge amount of energy is released. It is interesting that such events are even more probable in space than the meeting of two stars.

However, not always "communication" of galaxies ends in a collision and explosion. A small system can pass through its large brother, disturbing its structure. So 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 is the galaxy Wheel of the cart in the constellation Sculptor.

In some cases, systems do not collide, but pass 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

According to scientists, it is possible that after some, rather long, time, the Milky Way will absorb its nearest satellite, 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 Way and the Andromeda Nebula. Now a huge neighbor separates from us about 2.9 million light years. Two galaxies approach each other at a speed of 300 km / s. Probable collision according to scientists will happen 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 such space structures as galaxies: types of galaxies, features of interaction, their differences and similarities, the future. In this area there are 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.