There are many amazing things in our Universe, and sometimes it seems more interesting than the most sophisticated science fiction. And now we want to talk about objects in deep space, which everyone has heard about, but at the same time not everyone has an idea of what it is about.
Red giant
There are many different stars: some are hotter, others are colder, some are large, others (conventionally) small. The giant star has a low surface temperature and a huge radius. Because of this, it has a high luminosity. A typical example is the red giant. Its radius can reach 800 solar, and its brightness can exceed the solar one by 10 thousand times. A star becomes a red giant when at its center all the hydrogen turns into helium, and hydrogen fusion continues at the periphery of the helium core. This leads to an increase in luminosity, expansion of the outer layers, and a decrease in surface temperature.
Aldebaran, Arcturus, Gakrux are examples of red giants. All these stars are included in the list of the brightest stars in the night sky. Moreover, red giants are not the most massive. There are red supergiants that are the largest stars in terms of size. Their radius can exceed the solar one by 1500 times.
In a broader sense, the red giant is a star in the final stage of evolution. Its further fate depends on the mass. If the mass is low, then such a star will transform into a white dwarf; if it is high, it will turn into a neutron star or a black hole. Red giants are different, but they all have a similar structure. We are talking, in particular, about a hot dense core and a very rarefied and extended shell. All this leads to an intense stellar wind - the outflow of matter from the star into interstellar space.
Double star
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This term refers to two gravitationally bound stars that revolve around a common center of mass. Sometimes you can find systems that consist of three stars. The binary star seems to be a very exotic phenomenon, but it is very common in the Milky Way galaxy. Researchers believe that about half of all stars in the Galaxy are binary systems (this is the second name of this phenomenon).
An ordinary star forms as a result of the compression of a molecular cloud due to gravitational instability. In the case of a double star, obviously, the situation is similar, but as for the reason for the separation, here scientists cannot come to a common opinion.
Brown dwarf
The brown dwarf is a very unusual object that is difficult to classify in any way. It occupies an intermediate position between a star and a gas planet. These objects have a mass comparable to 1-8% of the sun. They are too massive for planets, and gravitational compression makes it possible for thermonuclear reactions involving "easily combustible" elements. But there is not enough mass to "ignite" hydrogen, and the brown dwarf shines for a relatively short time in comparison with an ordinary star.
The surface temperature of a brown dwarf can be 300-3000 K. It cools down continuously throughout its life: the larger such an object, the slower this process occurs. Simply put, a brown dwarf, due to thermonuclear fusion, heats up at the very first stage of its life, and then cools down, becoming like an ordinary planet. The name comes from the deep red or even infrared color of these objects.
Nebula
We hear this word more than once when we touch upon questions of astronomy. A nebula is nothing more than a cosmic cloud, which is composed of dust and gas. It is the basic building block of our universe: stars and stellar systems are formed from it. The nebula is one of the most beautiful astronomical objects, it can glow with all the colors of the rainbow.
The Andromeda Nebula (or Andromeda Galaxy) is the closest galaxy to the Milky Way. It is located at a distance of 2.52 million sv. years from Earth and contains approximately 1 trillion stars. Perhaps humanity will reach the Andromeda nebula in the distant future. And even if this does not happen, the nebula itself will "come to visit", swallowing the Milky Way. The fact is that the Andromeda nebula is much larger than our Galaxy.
It is important to clarify here. The word "nebula" has a long history: it used to be used to designate almost any astronomical object, including galaxies. For example, the Andromeda Nebula galaxy. Now they have moved away from this practice, and the word "nebula" denotes accumulations of dust, gas and plasma. They distinguish an emission nebula (a cloud of high temperature gas), a reflection nebula (it does not emit its own radiation), a dark nebula (a dust cloud that blocks light from objects located behind it) and a planetary nebula (a shell of gas produced by a star at the end of its evolution) … This also includes supernova remnants.
Yellow dwarf
Not everyone knows about this type of stars. And this is strange, because our own Sun is a typical yellow dwarf. Yellow dwarfs are small stars with a mass of 0.8–1.2 solar masses. These are the so-called luminaries. main sequence. On the Hertzsprung-Russell diagram, it is a region containing stars that use a thermonuclear fusion of helium from hydrogen as an energy source.
Yellow dwarfs have surface temperatures of 5000–6000 K, and the average lifetime of such a star is 10 billion years. Such stars turn into red giants after their supply of hydrogen is burned up. A similar fate awaits our Sun: according to scientists' forecasts, in about 5-7 billion years it will swallow our planet, and then turn into a white dwarf. But long before all this, life on our planet will be burned.
White dwarf
A dwarf star is the exact opposite of a giant star. Before us is an evolved star, the mass of which can be comparable to the mass of the Sun. In this case, the radius of the white dwarf is about 100 times smaller than the radius of our star. As one of the low-mass stars, the Sun will also turn into a white dwarf several billion years after the hydrogen reserves in the core are exhausted. White dwarfs occupy 3–10% of the stellar population of our Galaxy, but due to their low luminosity it is very difficult to identify them.
An "elderly" white dwarf is no longer directly white. The name itself came from the color of the first open stars, for example, Sirius B (the size of the latter, by the way, can be quite comparable with the size of our Earth). In fact, a white dwarf is not a star at all, since thermonuclear reactions no longer take place in its interior. Simply put, the white dwarf is not a star, but its "corpse".
As it evolves further, the white dwarf cools even more, and in addition, its color changes from white to red. The final stage in the evolution of such an object is a cooled black dwarf. Another option is the accumulation of matter on the surface of a white dwarf "overflowing" from another star, compression and subsequent explosion of a new or supernova.
Supernova
A supernova is a phenomenon in which the brightness of a star changes by 4-8 orders of magnitude, and after that one can see a gradual fading of the flare. In a broader sense, it is a star explosion, in which the entire object is destroyed. At the same time, such a star eclipses other stars for some time: and this is not surprising, because during an explosion its luminosity can exceed the solar one by 1000 million times. In a galaxy that can be compared to ours, the appearance of one supernova is recorded about once every 30 years. However, a huge amount of dust interferes with the observation of the object. During the explosion, a huge volume of matter falls into interstellar space. The leftover matter can act as a building material for a neutron star or black hole.
Our star and the planets of the solar system originated in a giant cloud of molecular gas and dust. Approximately 4.6 billion began the compression of this cloud, the first hundred thousand years after that the Sun was a collapsing protostar. However, over time, it stabilized and took on its present appearance. However, the Sun will not exist forever: first it will turn into a red giant, and then into a white dwarf.
There are two main types of supernovae. In the first case, there is a deficiency of hydrogen in the optical spectrum. Therefore, scientists believe that there was an explosion of a white dwarf. The fact is that the white dwarf has almost no hydrogen, since this is the end of stellar evolution. In the second case, researchers record traces of hydrogen. Hence the assumption arises that we are talking about the explosion of an "ordinary" star, the core of which has undergone a collapse. In this scenario, the core could eventually become a neutron star.
Neutron star
A neutron star is an object consisting mainly of neutrons - heavy elementary particles that have no electrical charge. As already mentioned, the reason for their formation is the gravitational collapse of normal stars. Due to attraction, the stellar masses begin to pull inward until they become incredibly compressed. As a result, the neutrons are "packed", as it were.
A neutron star is small - usually its radius does not exceed 20 km. Moreover, the mass of most of these objects is 1.3–1.5 solar masses (the theory assumes the existence of neutron stars with a mass of 2.5 solar masses). The density of a neutron star is so great that one teaspoon of its substance will weigh billions of tons. Such an object consists of an atmosphere of hot plasma, external and internal crust, and nuclei (external and internal).
Pulsar
It is believed that a neutron star emits a radio beam in the direction associated with its magnetic field, the axis of symmetry of which does not coincide with the axis of rotation of the star. Simply put, a pulsar is a neutron star that spins at incredible speeds. Pulsars emit powerful gamma rays, so we can observe radio waves if the neutron star is located with its pole to our planet. This can be compared to a lighthouse: it seems to the observer on the shore that he periodically blinks, although in fact the searchlight is simply turning in the other direction.
In other words, we can observe some neutron stars as pulsars due to the fact that they have electromagnetic waves that are ejected from the poles of the neutron star in beams. The best studied pulsar is PSR 0531 + 21, which is located in the Crab Nebula at a distance of 6520 sv. years from us. The neutron star makes 30 revolutions per second, and the total radiation power of this pulsar is 100,000 times higher than that of the Sun. However, many aspects of pulsars remain to be studied.
Quasar
Pulsar and quasar are sometimes confused, but the difference between them is very large. Quasar is a mysterious object, whose name comes from the phrase "quasi-stellar radio source". Such objects are some of the brightest and most distant from us. In terms of radiation power, a quasar can exceed all the stars of the Milky Way combined by a hundred times.
Of course, the discovery of the first quasar in 1960 sparked incredible interest in the phenomenon. Now scientists believe that we have an active galactic nucleus. There is a supermassive black hole that pulls matter out of the space that surrounds it. The mass of the hole is simply gigantic, and the radiation power exceeds the radiation power of all stars located in the galaxy. One of the versions also says that a quasar may be a galaxy at the earliest stage of development - at this time the surrounding matter is "devoured" by a supermassive black hole. The closest quasar to us is located at a distance of 2 billion light years, and the most distant, due to their incredible visibility, we can observe at a distance of 10 billion light years.
Blazar
There are also objects called blazars. They are the sources of the most powerful gamma-ray bursts in space. Blazars are streams of radiation and matter directed towards the Earth. Simply put, a blazar is a quasar that emits a powerful plasma beam that can destroy all life in its path. If such a ray passes at a distance of at least 10 sv. years from the Earth, there will be no life on it. Blazar is inextricably linked to the supermassive black hole at the center of the galaxy.
The name itself comes from the words "quasar" and "BL Lizards". The latter is a typical representative of the blazars known as the Lacertids. This class is distinguished by the features of the optical spectrum, which is devoid of broad emission lines characteristic of quasars. Now scientists have figured out the distance to the most distant blazar PKS 1424 + 240: it is 7.4 billion light years.
Black hole
Without a doubt, this is one of the most mysterious objects in the universe. Much has been written about black holes, but their nature is still hidden from us. The properties of objects are such that their second cosmic speed exceeds the speed of light. Nothing can escape the gravity of a black hole. It is so huge that it practically stops the passage of time.
A black hole forms from a massive star that has used up its fuel. A star that collapses under its own weight and drags along the space-time continuum around it. The gravitational field becomes so strong that even light can no longer escape from it. As a result, the region in which the star was previously located becomes a black hole. In other words, a black hole is a curved section of the universe. He sucks in the matter located nearby. The first key to understanding black holes is believed to be Einstein's theory of relativity. However, the answers to all the basic questions have yet to be found out.
Mole Hole
Continuing the topic, you simply cannot pass by the so-called. "Wormholes" or "wormholes". Even though this is a purely hypothetical object, we have before us a kind of space-time tunnel, consisting of two entrances and a throat. A wormhole is a topological feature of space-time that allows (hypothetically) travel by the shortest path of all. To understand at least a little the nature of a wormhole, you can roll a piece of paper and then pierce it with a needle. The resulting hole will be like a wormhole.
At different times, experts have put forward different versions of wormholes. The possibility of the existence of something like this proves the general theory of relativity, but so far not a single wormhole has been found. Perhaps, in the future, new studies will help clarify the nature of such objects.
Dark matter
This is a hypothetical phenomenon that does not emit electromagnetic radiation and does not directly interact with it. Therefore, we cannot detect it directly, but we see signs of the existence of dark matter when observing the behavior of astrophysical objects and the gravitational effects that they create.
But how did you find dark matter? The researchers calculated the total mass of the visible part of the Universe, as well as gravitational indicators. A certain imbalance was revealed, which was attributed to a mysterious substance. It also turned out that some galaxies are rotating faster than they should be according to calculations. Consequently, something influences them and does not allow them to "fly away" to the sides.
Scientists now believe that dark matter cannot be composed of ordinary matter and that it is based on tiny exotic particles. But some doubt this, pointing out that dark matter can also be composed of macroscopic objects.
Dark energy
If there is anything more mysterious than dark matter, it is dark energy. Unlike the first, dark energy is a relatively new concept, but it has already managed to turn our idea of the Universe upside down. Dark energy, according to scientists, is something that causes our universe to expand with acceleration. In other words, it is expanding faster and faster. Based on the hypothesis of dark matter, the mass distribution in the Universe looks like this: 74% is dark energy, 22% is dark matter, 0.4% is stars and other objects, 3.6% is intergalactic gas.
If in the case of dark matter there is at least indirect evidence of its existence, then dark energy exists purely within the framework of a mathematical model that considers the expansion of our Universe. Therefore, no one can now say with certainty what dark energy is.
Ilya Vedmedenko