A galaxy is a large formation of stars, gas, and dust that is held together by gravity. These largest compounds in the Universe can vary in shape and size. Most space objects are part of a particular galaxy. These are stars, planets, satellites, nebulae, black holes and asteroids. Some of the galaxies have large amounts of invisible dark energy. Due to the fact that galaxies are separated by empty space, they are figuratively called oases in the cosmic desert.
| Elliptical galaxy | Spiral galaxy | Wrong galaxy | |
|---|---|---|---|
| Spheroidal component | The entire galaxy | Eat | Very weak |
| Star disk | None or weakly expressed | Main component | Main component |
| Gas and dust disk | No | Eat | Eat |
| Spiral branches | No or only near the core | Eat | No |
| Active cores | Meet | Meet | No |
| 20% | 55% | 5% |
Our galaxy
The closest star to us, the Sun, is one of the billion stars in the Milky Way galaxy. Looking at the starry night sky, it’s hard not to notice a wide strip strewn with stars. The ancient Greeks called the cluster of these stars the Galaxy.
If we had the opportunity to look at this star system from the outside, we would notice an oblate ball in which there are over 150 billion stars. Our galaxy has dimensions that are hard to imagine. A ray of light travels from one side to the other for hundreds of thousands of Earth years! The center of our Galaxy is occupied by a core, from which huge spiral branches filled with stars extend. The distance from the Sun to the core of the Galaxy is 30 thousand light years. The solar system is located on the outskirts of the Milky Way.
Stars in the Galaxy, despite the huge accumulation of cosmic bodies, are rare. For example, the distance between the nearest stars is tens of millions of times greater than their diameters. It cannot be said that stars are scattered randomly in the Universe. Their location depends on the gravitational forces that hold the celestial body in a certain plane. Stellar systems with their own gravitational fields are called galaxies. In addition to stars, the galaxy includes gas and interstellar dust.
Composition of galaxies.
The Universe is also made up of many other galaxies. The closest ones to us are distant at a distance of 150 thousand light years. They can be seen in the sky of the southern hemisphere in the form of small foggy spots. They were first described by Pigafett, a member of the Magellanic expedition around the world. They entered science under the name of the Large and Small Magellanic Clouds.
The closest galaxy to us is the Andromeda Nebula. It is very large in size, so it is visible from Earth with ordinary binoculars, and in clear weather, even with the naked eye.
The very structure of the galaxy resembles a giant spiral convex in space. On one of the spiral arms, ¾ of the distance from the center, is the Solar System. Everything in the galaxy revolves around the central core and is subject to the force of its gravity. In 1962, astronomer Edwin Hubble classified galaxies depending on their shape. The scientist divided all galaxies into elliptical, spiral, irregular and barred galaxies.
In the part of the Universe accessible to astronomical research, there are billions of galaxies. Collectively, astronomers call them the Metagalaxy.
Galaxies of the Universe
Galaxies are represented by large groups of stars, gas, and dust held together by gravity. They can vary significantly in shape and size. Most space objects belong to some galaxy. These are black holes, asteroids, stars with satellites and planets, nebulae, neutron satellites.
Most galaxies in the Universe contain enormous amounts of invisible dark energy. Since the space between different galaxies is considered empty, they are often called oases in the void of space. For example, a star called the Sun is one of the billions of stars in the Milky Way galaxy located in our Universe. The Solar System is located ¾ of the distance from the center of this spiral. In this galaxy, everything constantly moves around the central core, which obeys its gravity. However, the core also moves with the galaxy. At the same time, all galaxies move at super speeds.
Astronomer Edwin Hubble in 1962 carried out a logical classification of the galaxies of the Universe, taking into account their shape. Now galaxies are divided into 4 main groups: elliptical, spiral, barred and irregular galaxies.
What is the largest galaxy in our Universe?
The largest galaxy in the Universe is a supergiant lenticular galaxy located in the Abell 2029 cluster.
Spiral galaxies
They are galaxies whose shape resembles a flat spiral disk with a bright center (core). The Milky Way is a typical spiral galaxy. Spiral galaxies are usually called with the letter S; they are divided into 4 subgroups: Sa, So, Sc and Sb. Galaxies belonging to the So group are distinguished by bright nuclei that do not have spiral arms. As for the Sa galaxies, they are distinguished by dense spiral arms tightly wound around the central core. The arms of Sc and Sb galaxies rarely surround the core.
Spiral galaxies of the Messier catalog
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Barred galaxies
Bar galaxies are similar to spiral galaxies, but have one difference. In such galaxies, spirals begin not from the core, but from the bridges. About 1/3 of all galaxies fall into this category. They are usually designated by the letters SB. In turn, they are divided into 3 subgroups Sbc, SBb, SBa. The difference between these three groups is determined by the shape and length of the jumpers, where, in fact, the arms of the spirals begin.
Spiral galaxies with the Messier catalog bar
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Elliptical galaxies
The shape of galaxies can vary from perfectly round to elongated oval. Their distinguishing feature is the absence of a central bright core. They are designated by the letter E and are divided into 6 subgroups (according to shape). Such forms are designated from E0 to E7. The former have an almost round shape, while the E7 are characterized by an extremely elongated shape.
Elliptical galaxies of the Messier catalog
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Irregular galaxies
They do not have any distinct structure or shape. Irregular galaxies are usually divided into 2 classes: IO and Im. The most common is the Im class of galaxies (it has only a slight hint of structure). In some cases, helical residues are visible. IO belongs to the class of galaxies that are chaotic in shape. The Small and Large Magellanic Clouds are a prime example of the Im class.
Irregular galaxies of the Messier catalog
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Table of characteristics of the main types of galaxies
| Elliptical galaxy | Spiral galaxy | Wrong galaxy | |
| Spheroidal component | The entire galaxy | Eat | Very weak |
| Star disk | None or weakly expressed | Main component | Main component |
| Gas and dust disk | No | Eat | Eat |
| Spiral branches | No or only near the core | Eat | No |
| Active cores | Meet | Meet | No |
| Percentage of total galaxies | 20% | 55% | 5% |
Large portrait of galaxies
Not long ago, astronomers began working on a joint project to identify the location of galaxies throughout the Universe. Their goal is to obtain a more detailed picture of the overall structure and shape of the Universe on large scales. Unfortunately, the scale of the universe is difficult for many people to comprehend. Take our galaxy, which consists of more than a hundred billion stars. There are billions more galaxies in the Universe. Distant galaxies have been discovered, but we see their light as it was almost 9 billion years ago (we are separated by such a great distance).
Astronomers learned that most galaxies belong to a certain group (it became known as a “cluster”). The Milky Way is part of a cluster, which in turn consists of forty known galaxies. Typically, most of these clusters are part of an even larger grouping called superclusters.
Our cluster is part of a supercluster, which is commonly called the Virgo cluster. Such a massive cluster consists of more than 2 thousand galaxies. At the time when astronomers created a map of the location of these galaxies, superclusters began to take a concrete form. Large superclusters have gathered around what appear to be giant bubbles or voids. What kind of structure this is, no one yet knows. We don't understand what might be inside these voids. According to the assumption, they may be filled with a certain type of dark matter unknown to scientists or have empty space inside. It will be a long time before we know the nature of such voids.
Galactic Computing
Edwin Hubble is the founder of galactic exploration. He is the first to determine how to calculate the exact distance to a galaxy. In his research, he relied on the method of pulsating stars, which are better known as Cepheids. The scientist was able to notice a connection between the period needed to complete one pulsation of brightness and the energy that the star releases. The results of his research became a major breakthrough in the field of galactic research. In addition, he discovered that there is a correlation between the red spectrum emitted by a galaxy and its distance (the Hubble constant).
Nowadays, astronomers can measure the distance and speed of a galaxy by measuring the amount of redshift in the spectrum. It is known that all galaxies in the Universe are moving away from each other. The farther a galaxy is from Earth, the greater its speed of movement.
To visualize this theory, just imagine yourself driving a car moving at a speed of 50 km per hour. The car in front of you is driving 50 km per hour faster, which means that its speed is 100 km per hour. There is another car in front of him, which is moving faster by another 50 km per hour. Even though the speed of all 3 cars will be different by 50 km per hour, the first car is actually moving away from you 100 km per hour faster. Since the red spectrum speaks about the speed of the galaxy moving away from us, the following is obtained: the greater the red shift, the faster the galaxy moves and the greater its distance from us.
We now have new tools to help scientists search for new galaxies. Thanks to the Hubble Space Telescope, scientists were able to see what they could only dream of before. The high power of this telescope provides good visibility of even small details in nearby galaxies and allows you to study more distant ones that have not yet been known to anyone. Currently, new space observation instruments are under development, and in the near future they will help to gain a deeper understanding of the structure of the Universe.
Types of galaxies
- Spiral galaxies. The shape resembles a flat spiral disk with a pronounced center, the so-called core. Our Milky Way galaxy falls into this category. In this section of the portal site you will find many different articles describing space objects of our Galaxy.
- Barred galaxies. They resemble spiral ones, only they differ from them in one significant difference. The spirals do not extend from the core, but from the so-called jumpers. One third of all galaxies in the Universe can be attributed to this category.
- Elliptical galaxies have different shapes: from perfectly round to oval elongated. Compared to spiral ones, they lack a central, pronounced core.
- Irregular galaxies do not have a characteristic shape or structure. They cannot be classified into any of the types listed above. There are much fewer irregular galaxies in the vastness of the Universe.
Astronomers have recently launched a joint project to identify the location of all the galaxies in the Universe. Scientists hope to get a clearer picture of its structure on a large scale. The size of the Universe is difficult for human thought and understanding to estimate. Our galaxy alone is a collection of hundreds of billions of stars. And there are billions of such galaxies. We can see light from discovered distant galaxies, but not even imply that we are looking into the past, because the light beam reaches us over tens of billions of years, such a great distance separates us.
Astronomers also associate most galaxies with certain groups called clusters. Our Milky Way belongs to a cluster that consists of 40 explored galaxies. Such clusters are combined into large groups called superclusters. The cluster with our galaxy is part of the Virgo supercluster. This giant cluster contains more than 2 thousand galaxies. After scientists began to draw a map of the location of these galaxies, superclusters acquired certain shapes. Most galactic superclusters were surrounded by giant voids. No one knows what could be inside these voids: outer space like interplanetary space or a new form of matter. It will take a long time to solve this mystery.
Interaction of galaxies
No less interesting for scientists is the question of the interaction of galaxies as components of cosmic systems. It's no secret that space objects are in constant motion. Galaxies are no exception to this rule. Some types of galaxies could cause a collision or merger of two cosmic systems. If you understand how these space objects appear, large-scale changes as a result of their interaction become more understandable. During the collision of two space systems, a gigantic amount of energy splashes out. The meeting of two galaxies in the vastness of the Universe is an even more probable event than the collision of two stars. Collisions of galaxies do not always end with an explosion. A small space system can freely pass by its larger counterpart, changing its structure only slightly.
Thus, the formation of formations occurs, similar in appearance to elongated corridors. They contain stars and gaseous zones, and new stars are often formed. There are times when galaxies do not collide, but only lightly touch each other. However, even such an interaction triggers a chain of irreversible processes that lead to huge changes in the structure of both galaxies.
What future awaits our galaxy?
As scientists suggest, it is possible that in the distant future the Milky Way will be able to absorb a tiny cosmic-sized satellite system, which is located at a distance of 50 light years from us. Research shows that this satellite has a long life potential, but if it collides with its giant neighbor, it will most likely end its separate existence. Astronomers also predict a collision between the Milky Way and the Andromeda Nebula. Galaxies move towards each other at the speed of light. The wait for a probable collision is approximately three billion Earth years. However, whether it will actually happen now is difficult to speculate due to the lack of data on the movement of both space systems.
Description of galaxies onKvant. Space
The portal site will take you to the world of interesting and fascinating space. You will learn the nature of the structure of the Universe, become familiar with the structure of famous large galaxies and their components. By reading articles about our galaxy, we become more clear about some of the phenomena that can be observed in the night sky.
All galaxies are at a great distance from Earth. Only three galaxies can be seen with the naked eye: the Large and Small Magellanic Clouds and the Andromeda Nebula. It is impossible to count all the galaxies. Scientists estimate that their number is about 100 billion. The spatial distribution of galaxies is uneven - one region may contain a huge number of them, while the second will not contain even a single small galaxy. Astronomers were unable to separate images of galaxies from individual stars until the early 90s. At this time, there were about 30 galaxies with individual stars. All of them were assigned to the Local Group. In 1990, a majestic event took place in the development of astronomy as a science - the Hubble Telescope was launched into Earth orbit. It was this technique, as well as new ground-based 10-meter telescopes, that made it possible to see a significantly larger number of resolved galaxies.
Today, the “astronomical minds” of the world are scratching their heads about the role of dark matter in the construction of galaxies, which manifests itself only in gravitational interaction. For example, in some large galaxies it makes up about 90% of the total mass, while dwarf galaxies may not contain it at all.
Evolution of galaxies
Scientists believe that the emergence of galaxies is a natural stage in the evolution of the Universe, which took place under the influence of gravitational forces. Approximately 14 billion years ago, the formation of protoclusters in the primary substance began. Further, under the influence of various dynamic processes, the separation of galactic groups took place. The abundance of galaxy shapes is explained by the diversity of initial conditions in their formation.
The contraction of the galaxy takes about 3 billion years. Over a given period of time, the gas cloud turns into a star system. Star formation occurs under the influence of gravitational compression of gas clouds. After reaching a certain temperature and density in the center of the cloud, sufficient for the start of thermonuclear reactions, a new star is formed. Massive stars are formed from thermonuclear chemical elements that are more massive than helium. These elements create the primary helium-hydrogen environment. During enormous supernova explosions, elements heavier than iron are formed. It follows from this that the galaxy consists of two generations of stars. The first generation is the oldest stars, consisting of helium, hydrogen and very small amounts of heavy elements. Second-generation stars have a more noticeable admixture of heavy elements because they form from primordial gas enriched in heavy elements.
In modern astronomy, galaxies as cosmic structures are given a special place. The types of galaxies, the features of their interaction, similarities and differences are studied in detail, and a forecast of their future is made. This area still contains a lot of unknowns that require additional study. Modern science has resolved many questions regarding the types of construction of galaxies, but there are also many blank spots associated with the formation of these cosmic systems. The current pace of modernization of research equipment and the development of new methodologies for studying cosmic bodies give hope for a significant breakthrough in the future. One way or another, galaxies will always be at the center of scientific research. And this is based not only on human curiosity. Having received data on the patterns of development of cosmic systems, we will be able to predict the future of our galaxy called the Milky Way.
The most interesting news, scientific, and original articles about the study of galaxies will be provided to you by the website portal. Here you can find exciting videos, high-quality images from satellites and telescopes that will not leave you indifferent. Dive into the world of unknown space with us!
More and more often you will come across various abbreviations and abbreviations that indicate types of galaxies, came to the conclusion that it is necessary to write a separate article on this topic in parallel and independently, so that if you have any questions or misunderstandings about the types of galaxies, you simply refer to this short article.
There are very few types of galaxies. There are 4 main ones, with 6 some additions. Let's figure it out.
Types of galaxies
Looking at the diagram above, let's go in order, let's figure out what the letter and the adjacent number (or another additional letter) mean. Everything will fall into place.
1. Elliptical galaxies (E)
Type E galaxy (M 49)
Elliptical galaxies have an oval shape. They lack a central bright core.
The number that is added after the English letter E divides this type into 7 subtypes: E0 - E6. (some sources report that there may be 8 subtypes, some 9, it doesn’t matter). It is determined by a simple formula: E = (a - b) / a, where a is the major axis, b is the minor axis of the ellipsoid. Thus, it is not difficult to understand that E0 is ideally round, E6 is oval or flattened.
Elliptical galaxies make up less than 15% of the total number of all galaxies. They lack star formation and consist mainly of yellow stars and dwarfs.
When observed through a telescope, they are not of great interest, because It will not be possible to examine the details in detail.
2. Spiral galaxies (S)
S-type galaxy (M 33)
The most popular type of galaxy. More than half of all existing galaxies are spiral. Our galaxy Milky Way is also spiral.
Because of their “branches” they are the most beautiful and interesting to observe. Most of the stars are located in close proximity to the center. Further, due to rotation, the stars scatter, forming spiral branches.
Spiral galaxies are divided into 4 (sometimes 5) subtypes (S0, Sa, Sb and Sc). In S0, the spiral branches are not expressed at all and have a light core. They are very similar to elliptical galaxies. They are often classified as a separate type - lenticular. Such galaxies make up no more than 10% of the total number. Next come Sa (often simply written S), Sb, Sc (sometimes Sd is also added) depending on the degree of twisting of the branches. The older the additional letter, the lower the degree of twist and the “branches” of the galaxy surround the core less and less often.
The “branches” or “arms” of spiral galaxies have many young ones. Active star formation processes take place here.
3. Spiral galaxies with bar (SB)
SBb type galaxy (M 66)
Spiral galaxies with bar(or also called “barred”) are a type of spiral galaxy, but contain a so-called “bar” that passes through the center of the galaxy - its core. Spiral branches (sleeves) diverge from the ends of these bridges. In ordinary spiral galaxies, branches radiate from the core itself. Depending on the degree of twisting of the branches, they are designated as SBa, SBb, SBc. The longer the sleeve, the older the additional letter.
4. Irregular galaxies (Irr)
Type Irr Galaxy (NGC 6822)
Irregular galaxies do not have any clearly defined form. They have a “ragged” structure, the core is not distinguishable.
No more than 5% of the total number of galaxies have this type.
However, even irregular galaxies have two subtypes: Im and IO (or Irr I, Irr II). Im have at least some hint of structure, some symmetry or visible boundaries. IO are completely chaotic.
5. Galaxies with polar rings
Polar Ring Galaxy (NGC 660)
This type of galaxy stands apart from others. Their peculiarity is that they have two stellar disks that rotate at different angles relative to each other. Many believe that this is possible due to the merger of two galaxies. But scientists still do not have an exact definition of how such galaxies were formed.
Majority polar ring galaxies are lenticular galaxies or S0. Although they are rarely seen, the sight is memorable.
6. Peculiar galaxies
Peculiar Tadpole Galaxy (PGC 57129)
Based on the definition from Wikipedia:
Peculiar galaxy is a galaxy that cannot be classified into a specific class, since it has pronounced individual characteristics. There is no clear definition for this term, and the assignment of galaxies to this type may be disputed.
They are unique in their own way. Finding them in the sky is not easy and requires professional telescopes, but what you see looks amazing.
That's all. I hope nothing complicated. Now you know the basics types (classes) of galaxies. And when getting acquainted with astronomy or reading articles on my blog, you will not have questions about their definition. And if, suddenly, you forget, immediately refer to this article.
In modern astronomy, the most widely used is the very first classification of galaxies, proposed by Edwin Powell Hubble in 1926, and subsequently refined by him, and then by Gerard de Vaucouleurs and Alan Sandage.
This classification is based on the shape of known galaxies. According to it, all galaxies are divided into 5 main types:
Elliptical (E);
Spiral (S);
Barred spiral galaxies (SB);
Incorrect (Irr);
Galaxies too dim to be classified are designated by Hubble as Q.
In addition, the galaxy designations in this classification use numbers to indicate how oblate the elliptical galaxy is and letters to indicate how tightly the arms of spiral galaxies adhere to the core.
Graphically, this classification is represented as a series called the Hubble sequence (or the Hubble tuning fork due to the similarity of the circuit with this instrument).
Elliptical galaxies (type E) make up 13% of the total number of galaxies. They look like a circle or ellipse, the brightness of which quickly decreases from the center to the periphery. Elliptical galaxies are very diverse in shape: they can be either spherical or very oblate. In this regard, they are divided into 8 subclasses - from E0 (spherical shape, no compression) to E7 (highest compression).
Elliptical galaxies are the simplest in structure. They consist mainly of old red and yellow giants, red, yellow and white dwarfs. There is no dust matter in them. Star formation in galaxies of this type has not occurred for several billion years. There is almost no cold gas or cosmic dust in them. Rotation has been detected only in the most compressed of elliptical galaxies.
Spiral galaxies- the most numerous type: they make up about 50% of all observed galaxies. Most of the stars in a spiral galaxy are located within the galactic disk. The galactic disk exhibits a spiral pattern of two or more branches or arms twisting in one direction, extending from the center of the galaxy.
There are two types of spirals. In the first type, designated SA or S, the spiral arms extend directly from the central seal. In the second, they begin at the ends of an oblong formation, in the center of which there is an oval seal. It appears that the two spiral arms are connected by a bridge, which is why such galaxies are called crossed spirals; they are designated by the symbol SB.
Spiral galaxies differ in the degree of development of their spiral structure, which is marked in the classification by adding the letters a, b, c to the symbols S (or SA) and SB.
The arms of spiral galaxies are bluish in color because they contain many young giant stars. All spiral galaxies rotate at significant speeds, so stars, dust and gases are concentrated in a narrow disk (Population I stars). Rotation in the vast majority of cases occurs in the direction of twisting of the spiral branches.
Each spiral galaxy has a central condensation. The color of clusters of spiral galaxies is reddish-yellow, indicating that they consist mainly of stars of spectral classes G, K, and M (that is, the smallest and coolest).
The abundance of gas and dust clouds and the presence of bright blue giants of spectral classes O and B indicate active star formation processes occurring in the spiral arms of these galaxies.
The disk of spiral galaxies is immersed in a rarefied, faintly luminous cloud of stars - a halo. The halo consists of young Population II stars forming numerous globular clusters.
In some galaxies, the central part is spherical and glows brightly. This part is called the bulge (from the English bulge - thickening, swelling). The bulge consists of old Population II stars and, often, a supermassive black hole at the center. Other galaxies have a “stellar bar” in the central part.
The most famous spiral galaxies are our Milky Way Galaxy and the Andromeda Nebula.
Lenticular galaxy(type S0) is an intermediate type between spiral and elliptical galaxies. In galaxies of this type, the bright central condensation (bulge) is highly compressed and looks like a lens, and the branches are absent or very faintly traced.
Lenticular galaxies consist of old giant stars, which is why their color is reddish. Two-thirds of lenticular galaxies, like ellipticals, do not contain gas; one-third has the same gas content as spiral galaxies. Therefore, star formation processes occur at a very slow pace. Dust in lenticular galaxies is concentrated near the galactic core. About 10% of known galaxies are lenticular galaxies.
For irregular or irregular galaxies (Ir) characterized by an irregular, patchy shape. Irregular galaxies are characterized by the absence of central densities and symmetrical structure, as well as low luminosity. Such galaxies contain a lot of gas (mainly neutral hydrogen) - up to 50% of their total mass. About 25% of all star systems belong to this type.
Irregular galaxies are divided into 2 large groups. The first of these, designated Irr I, includes galaxies with a hint of a certain structure. The Irr I division is not final: for example, if the galaxy under study shows a semblance of spiral arms (characteristic of S-type galaxies), the galaxy receives the designation Sm or SBm (has a bar in its structure); if such a phenomenon is not observed, the designation is Im.
The second group of irregular galaxies (Irr II) includes all other galaxies with a chaotic structure.
There is also a third group of irregular galaxies - dwarf galaxies, designated as dI or dIrrs. Dwarf irregular galaxies are believed to be similar to the earliest galactic formations that existed in the Universe. Some are small spiral galaxies destroyed by the tidal forces of more massive companions.
Typical representatives of such galaxies are the Large and Small Magellanic Clouds. In the past, the Large and Small Magellanic Clouds were thought to be irregular galaxies. However, they were later discovered to have a helical structure with a bar. Therefore, these galaxies were reclassified as SBm, the fourth type of barred spiral galaxy.
Galaxies that have certain individual characteristics that do not allow them to be classified into any of the classes listed above are called peculiar.
An example of a peculiar galaxy is the radio galaxy Centaurus A (NGC 5128).
The Hubble classification is currently the most common, but not the only one. In particular, the de Vaucouleurs System, which is a more expanded and revised version of the Hubble classification, and the Yerkes System, in which galaxies are grouped depending on their spectra, shape and degree of concentration towards the center, are widely used.
galaxy list, galaxy list
Some galaxies are listed below.
- 1 Notable galaxies
- 2 Galaxies with proper names
- 3 Visible to the naked eye
- 4 First
- 4.1 Prototypes
- 5 Extreme people
- 5.1 Distances
- 6 Objects Mistaken for Galaxies
- 7 Lists of galaxies
- 8 See also
- 9 Notes
Notable galaxies
| Galaxy | Notes |
|---|---|
| M82 | Prototype galaxy with a burst of star formation. |
| M87 | The central galaxy in the Virgo Cluster, the central cluster in the local supercluster of galaxies. |
| M102 | Not fully identified object. According to one of the most common hypotheses, this is the galaxy NGC 5866, according to another - a duplicate of the galaxy M101. |
| NGC 2770 | Referred to as a "supernova factory" due to the three supernovae that recently exploded there. |
| NGC 3314A, NGC 3314B | A pair of spiral galaxies that overlap each other, are at different distances from Earth, and are not connected to each other. A rare case of visual superposition of galaxies. |
| ESO 137-001 | Located in the Abell 3627 galaxy cluster, this galaxy is deprived of interstellar gas under intergalactic pressure due to the high speed of passage through the cluster and leaves a dense tail with a large number of forming stars. The tail is the largest star-forming region outside galaxies known to date. The galaxy is similar to a comet, with a galaxy at the head and a tail of gas and stars. |
| Galaxy Comet | Located in the galaxy cluster Abell 2667, this spiral galaxy is stripped of stars and gas as it moves at high speed through the cluster, giving it the appearance of a comet. |
Galaxies with proper names
| Galaxy | origin of name |
|---|---|
| Milky Way | Based on the appearance of the nebula formed by this galaxy in the night sky (resembles a path of milk). |
| Large Magellanic Cloud | By the name of Ferdinand Magellan, who observed them in 1519 during his trip around the world. |
| Small Magellanic Cloud | |
| Andromeda Galaxy | According to the constellations in which they are located. |
| Galaxy Sculptor (aka Galaxy Silver Coin) | |
| Triangulum Galaxy | |
| Bode Galaxy | After the name of Elert Bode, who discovered it in 1774. |
| Meyola Object | After the name of Nicholas Mayol, who discovered it in 1940. |
| Hoag's facility | After the name of Arthur Hoag, who discovered it in 1950. |
| Whirlpool Galaxy | So named because of its visual resemblance to a whirlpool (at the time of its discovery it was the first galaxy with a clearly defined spiral structure). |
| Galaxy Antennas | Due to visual similarity to related items. |
| Spindle Galaxy | |
| Galaxy Tadpole | |
| Galaxy Cartwheel | |
| Galaxy Comet | |
| Galaxy Mouse | |
| Sunflower Galaxy | |
| Galaxy Cigar | |
| Galaxy Silver Coin (aka Galaxy Sculptor) | |
| Galaxy Sombrero | |
| Galaxy Fireworks | |
| Pinwheel Galaxy | |
| Black Eye Galaxy (aka Sleeping Beauty Galaxy) | |
| South Pinwheel Galaxy | |
| Sleeping Beauty Galaxy (aka Black Eye Galaxy) |
Visible to the naked eye
Galaxies visible to the naked eye to an observer with keen vision under very dark skies during clear weather.
| Galaxy | Visible Pollution | Distance | Notes |
|---|---|---|---|
| Milky Way | −26.74 (Sun) | 0 | Our galaxy. Most objects visible to the naked eye in the sky. |
| Large Magellanic Cloud | 0,9 | 160 thousand St. years (50 kpc) | Visible only in the southern hemisphere. The brightest nebula in the sky. |
| Small Magellanic Cloud (NGC 292) | 2,7 | 200 thousand St. years (60 kpc) | Visible only in the southern hemisphere. |
| Andromeda Galaxy (M31, NGC 224) | 3,4 | 2.5 million St. years (780 kpc) | Also called the Andromeda Nebula. Located in the constellation Andromeda. |
| Triangulum Galaxy (M33, NGC 598) | 5,7 | 2.9 million St. years (900 kpc) | Observation with the naked eye is very difficult. |
| Bode Galaxy (M81, NGC 3031) | 6,9 | 12 million St. years (3.6 Mpc) | It is the most distant object visible to the naked eye. The only more distant thing that could be seen was GRB 080319B at magnitude 0.937, but this was temporary. |
The Sagittarius Dwarf Elliptical Galaxy is not listed because it is not visible in the sky as a separate galaxy.
First
| First | Galaxy | date | Notes | ||||
|---|---|---|---|---|---|---|---|
| First galaxy | Milky Way and Andromeda Galaxy | 1918 | Ernst Epic determined the distance to the Andromeda nebula and found that it could not be part of the Milky Way. So it became clear that the Milky Way is not the entire Universe. The value obtained by Epic is close to the modern one. In 1923, Edwin Hubble determined the distance to the Andromeda nebula in a different way, obtaining a value 3 times less than the modern one, although indicating the location of the Andromeda nebula outside the Milky Way. | ||||
| First radio galaxy | Swan A | 1952 | The first of several objects later named radio stars, Cygnus A was identified as a distant galaxy. | ||||
| First quasar | 3C273 3C48 |
1962 1960 |
3C273 was the first quasar for which a redshift was determined, and is therefore referred to by some as the first quasar. Others consider the first quasar to be the first radio star 3C48, for which it was not possible to determine the spectrum. | ||||
| First Seyfert galaxy | M77 (NGC 1068) | 1908 | The features of Seyfert galaxies were first observed in M77 in 1908. However, they were allocated to the class only in 1943. | ||||
| First relativistic jet | 3C279 | 1971 | The jet is emitted by a quasar. | The first relativistic jet from a Seyfert galaxy | III Zw 2 | 2000 | |
| First spiral galaxy | Whirlpool Galaxy | 1845 | Lord William Parsons discovered a spiral structure in the white nebula M51. |
Prototypes
This is a list of the first galaxies that became the prototypes of the galaxy classes.
Extreme sportsmen
Distances
| Name | Galaxy | Distance | Notes |
|---|---|---|---|
| Nearest neighboring galaxy | Dwarf Galaxy in Canis Major | 25 thousand St. years | Discovered in 2003. A satellite of the Milky Way, slowly being absorbed by it. |
| Most distant galaxy | UDFj-39546284 | z = 11.9 | Discovered in 2011. The most distant galaxy generally recognized for which the redshift has been determined. |
| Nearest quasar | 3C 273 | z = 0.158 | First identified quasar. |
| The most distant quasar | CFHQS J2329-0301 | z = 6.43enkn65 | Opened in 2007. |
| Nearest radio galaxy | Centaurus A (NGC 5128, PKS 1322-427) | 13.7 million St. years | |
| Most distant radio galaxy | TN J0924-2201 | z = 5.2 | |
| Nearest Seyfert galaxy | Compass | 13 million St. years | It is also the closest Type II Seyfert galaxy. The closest type I galaxy is NGC 4151. |
| The most distant Seyfert galaxy | z = | ||
| Nearest blazar | Markaryan 421 (Mrk 421, Mkn 421, PKS 1101+384, LEDA 33452) | z = 0.03 | This is a BL Lac object. |
| The most distant blazar | Q0906+6930 | z = 5.47 | |
| Nearest BL Lac object | Markaryan 421 (Mkn 421, Mrk 421, PKS 1101+384, LEDA 33452) | z = 0.03 | |
| The most distant BL Lac object | z = | ||
| Nearest LINER | |||
| The most distant LINER | z = | ||
| Nearest LIRG | |||
| The most distant LIRG | z = | ||
| Nearest ULIRG | IC 1127 (Arp 220, APG 220) | z = 0.018 | |
| The most distant ULIRG | z = | ||
| Nearest starburst galaxy | Cigar Galaxy (M82, Arp 337/APG 337, 3C 231, Ursa Major A) | 3.2 Mpc |
Objects Mistaken for Galaxies
Lists of galaxies
See also: Local group| Galaxy | Distance (million light years) |
Constellation | Type |
|---|---|---|---|
| CMa Dwarf | 0,025 | Big dog | Irr |
| SagDEG | 0,065 | Sagittarius | dSph(t) |
| UMa II | 0,098 | Big Dipper | dSph |
| BMO | 0,168 | Golden Fish Table Mountain | SBm |
| MMO (NGC 292) | 0,2 | Toucan | SBm |
| PGC 3589 | 0,29 | Sculptor | dE0 |
| UMa I | 0,33 | Big Dipper | dSph |
| PGC 10074 | 0,46 | Bake | dE0 |
| PGC 19441 | 0,46 | Keel | E3 |
| PGC 6830 | 1,44 | Phoenix | IAm |
| NGC 6822 | 1,63 | Sagittarius | IBM |
| NGC 185 | 2,05 | Cassiopeia | E |
| NGC 147 | 2,2 | Cassiopeia | dE5 |
| IC 10 | 2,2 | Cassiopeia | dIrr IV/BCD |
| M33 | 2,4 | Triangle | Sc |
| M31 | 2,5 | Andromeda | Sb |
| M32 | 2,9 | Andromeda | E2 |
| M110 | 2,9 | Andromeda | E5 |
| NGC 3109 | 2,9 | Hydra | Sbm |
| WLM (PGC 143) | 3,04 | Whale | IB(s)m |
| NGC 300 | 7 | Sculptor | Scd |
| NGC 55 | 7,2 | Sculptor | Sbm |
| NGC 404 | 10 | Andromeda | SA(s)0 |
| IC 342 | 10,7 | Giraffe | Sab |
| NGC 1569 | 11 | Giraffe | IBM |
| NGC 247 | 11,8 | Whale | SBcd |
| NGC 5128 | 12 | Centaurus | S0 |
| NGC 4449 | 12 | Hounds Dogs | IBM |
| M81 | 12 | Big Dipper | Sb |
| M82 | 12 | Big Dipper | I0 |
| NGC 247 | 12,7 | Phoenix | SB(s)m |
| NGC 7793 | 12,7 | Sculptor | SA(s)d |
| NGC 3077 | 12,8 | Big Dipper | Sc |
| ESO 97-G13 | 13 | Compass | SA(s)b |
| M108 | 14,1 | Big Dipper | Sd |
| M83 | 15 | Hydra | Sc |
| M94 | 16 | Hound Dogs | Sab |
| NGC 1705 | 17 | Painter | E-S0 |
| M106 | 23,7 | Hound Dogs | SBbc |
| M65 | 24 | a lion | Sa |
| M64 | 24 | Veronica's hair | Sab |
| M101 | 27 | Big Dipper | SA(sr)c |
| M104 | 29,5 | Virgo | Sa |
| M74 | 30 | Fish | Sc |
| M96 | 31 | a lion | SBab |
| M105 | 32 | a lion | E1 |
| NGC 5195 | 32 | Hound Dogs | S0 |
| M95 | 32,6 | a lion | SBb |
| M66 | 35 | a lion | Sb |
| M51 | 37 | Hound Dogs | SAbc |
| M63 | 37 | Hound Dogs | Sbc |
| NGC 4656 | 40 | Hound Dogs | SB(s)m |
| NGC 5866 | 44 | The Dragon | S0-a |
| NGC 4038 | 45 | Crow | SBm |
| M109 | 46,3 | Big Dipper | SBbc |
| M88 | 47,5 | Veronica's hair | Sb |
| M49 | 49,5 | Virgo | E2 |
| M89 | 50 | Virgo | E |
| M61 | 52 | Virgo | SBbc |
| M100 | 52,5 | Veronica's hair | SBbc |
| M90 | 58,7 | Virgo | SBab |
| M85 | 60 | Veronica's hair | S0-a |
| M98 | 60 | Veronica's hair | SBb |
| M99 | 60 | Veronica's hair | Sc |
| M87 | 60 | Virgo | E1 |
| M59 | 60 | Virgo | E5 |
| M60 | 60 | Virgo | E2 |
| M84 | 60 | Virgo | E1 |
| NGC 1300 | 61,3 | Eridanus | (R")SB(s)bc |
| NGC 1427A | 62 | Eridanus | IBM |
| NGC 4414 | 62,3 | Veronica's hair | SBb |
| M91 | 63 | Veronica's hair | SBb |
| NGC 4039 | 65 | Crow | SBm |
| M58 | 68 | Virgo | SBb |
| NGC 2207 | 81 | Big Dog | SAB(rs)bc pec |
| NGC 4676 | 290 | Veronica's hair | SB0-a |
| BX442 | 1070 | Pegasus | Sc |
see also
- Galaxy
- Milky Way
- Local group
- Galaxy cluster
- List of nearby galaxies
- List of spiral galaxies
Notes
- Sky and Telescope, New Stars in a Galaxy's Wake, 28 September 2007
- NASA, "Orphan" Stars Found in Long Galaxy Tail, 09.20.07
- arXiv, H-alpha tail, intracluster HII regions and star-formation: ESO137-001 in Abell 3627, Fri, 8 June 2007 17:50:48 GMT
- Universe Today, Galaxy Leaves New Stars Behind in Its Death Plunge; September 20th, 2007
- Astronomy Knowledge Base, Magellanic Cloud, UOttawa
- SEDS, The Large Magellanic Cloud, LMC
- SEDS, The Small Magellanic Cloud, SMC
- Dave Snyder. University Lowbrow Astronomers Naked Eye Observer's Guide. Umich.edu (February, 2000). Retrieved November 1, 2008. Archived from the original on March 31, 2012.
- 1 2 Farthest Naked Eye Object. Uitti.net. Retrieved November 1, 2008. Archived from the original on March 31, 2012.
- SEDS, Messier 33
- SEDS, Messier 81
- Astrophys. J., 55, 406-410 (1922)
- Astrophysical Journal, Centennial Issue, Vol. 525C, p. 569; Baade & Minkowski's Identification of Radio Sources; 1999ApJ…525C.569B
- SEDS, Seyfert Galaxies
- Astronomy and Astrophysics, v.357, p.L45-L48 (2000) III Zw 2, the first superluminal jet in a Seyfert galaxy; 2000A&A…357L..45B
- SEDS, Lord Rosse’s drawings of M51, his “Question Mark” “Spiral Nebula”
- Sub-parsec-scale structure and evolution in Centaurus A Introduction; Tue November 26 15:27:29 PST 1996
- 1 2 The 2006 Giant Flare in PKS 2155-304 and Unidentified TeV Sources
- 1 2 Julie McEnery. Time Variability of the TeV Gamma-Ray Emission from Markarian 421. Iac.es. Retrieved November 1, 2008. Archived from the original on March 31, 2012.
- bNet, Ablaze from afar: astronomers may have identified the most distant “blazar” yet, Sept, 2004
- arXiv, Q0906+6930: The Highest-Redshift Blazar, 9 June 2004
- Monthly Notices of the Royal Astronomical Society, Volume 384, Issue 3, pp. 875-885; Optical spectroscopy of Arp220: the star formation history of the closest ULIRG; 03/2008 ; 2008MNRAS.384..875R
- Chandra Proposal ID #01700041 ; ACIS Imaging of the Starburst Galaxy M82; 09/1999; 1999cxo..prop..362M
- Starburst Galaxies: Proceedings of a Workshop (page 27) ; 2001; ISBN 3-540-41472-X
| Galaxies | |
|---|---|
| Kinds |
Elliptical (E) Spiral (S) Barred Spiral (SB) Lenticular (S0) Irregular (Irr) Dwarf (d) Dwarf Irregular (dI) Dwarf Elliptical (dE) Dwarf Spheroidal (dSph) Ultra-Compact Dwarf (UCD) Annular Polar Ring |
| Structure |
Supermassive black hole Bulge Jumper Disk Core Spiral arm Halo Polar ring Protogalaxy |
| Active cores |
Relativistic jet Seyfert galaxy Radio galaxy Lacertida Quasar |
| Interaction |
Interacting galaxies Flare-up galaxy Satellite Cluster Supercluster Void Star stream |
| Phenomena and processes |
Emergence and evolution Gravitational lens Peculiar galaxy Galactic year Metagalaxy Galactic filament Great wall (Sloan, CfA2, Hercules - Corona Borealis) Great attractor |
| Lists |
Local Group Nearest Spirals Atlas of Peculiar Galaxies |
galaxy craft list, galaxy football list, galaxy list, galaxy list
List of galaxies Information About
There are three main types of galaxies: spiral, elliptical and irregular. The first include, for example, the Milky Way and Andromeda. In the center are objects and a black hole, around which a halo of stars and dark matter revolves. Arms branch off from the core. The spiral shape is formed due to the fact that the galaxy does not stop rotating. Many representatives have only one sleeve, but some have three or more.
Table of characteristics of the main types of galaxies
Spiral ones come with or without a jumper. In the first type, the center is crossed by a dense bar of stars. And in the latter, such formation is not observed.
Elliptical galaxies contain the oldest stars and do not have enough dust and gas to create young ones. They may resemble a circle, oval or spiral type in shape, but without sleeves.
About a quarter of the galaxies are irregular groups. They are smaller than spiral ones and sometimes display bizarre shapes. They can be explained by the appearance of new stars or gravitational contact with a neighboring galaxy. Among the incorrect ones are .
There are also many galactic subtypes: Seyfert (fast-moving spirals), bright elliptical supergiants (absorb others), ring supergiants (without a core), and others.