as well as many other sources, we get a very consistent picture of the universe. It is composed of 68% dark energy, 27% dark matter, 4.9% ordinary matter, 0.1% neutrinos, 0.01% radiation, and is about 13.8 billion years old. The uncertainty in the age of the universe is around 100 million years, so while the universe could certainly be a hundred million years younger or older, it is unlikely to reach 14.5 billion years.
ESA's Gaia mission measured the positions and properties of hundreds of millions of stars near the galactic center and found the oldest stars known to mankind
There is only one sensible possibility left: perhaps we are wrong in estimating the age of the stars. We have studied hundreds of millions of stars in detail at different stages of their lives. We know how stars form and under what conditions; we know when and how they ignite nuclear fusion; we know how long the various stages of synthesis last and how effective they are; we know how long they live and how they die, different types with different masses. In short, astronomy is a serious science, especially when it comes to stars. In general, the oldest stars are relatively low mass (less massive than our Sun), contain few metals (elements other than hydrogen and helium), and may be older than the galaxy itself.
Globular clusters contain extremely old stars
Many of them are in globular clusters, which, for sure, contain stars 12 billion or, in rare cases, even 13 billion years old. A generation ago, people claimed that these clusters were 14-16 billion years old, which created tension in established cosmological models, but gradually improved understanding of stellar evolution brought these numbers in line with the norm. We have developed more advanced methods to improve our observational abilities, not only by measuring the carbon, oxygen, or iron content of these stars, but also by using the radioactive decay of uranium and thorium. We can directly determine the age of individual stars.
SDSS J102915+172927 is an ancient star 4140 light years away, containing only 1/20,000 of the heavy elements of our Sun, and should be 13 billion years old. This is one of the oldest stars in the universe.
In 2007, we were able to measure the star HE 1523-0901, which is 80% of the Sun's mass, contains only 0.1% solar iron, and is believed to be 13.2 billion years old, based on its abundance of radioactive elements. In 2015, nine stars were identified near the center of the Milky Way that formed 13.5 billion years ago: just 300,000,000 years after the Big Bang. "These stars formed before the Milky Way and the galaxy formed around them," says Louis Howes, co-discoverer of these ancient relics. In fact, one of these nine stars has less than 0.001% solar iron; this is the type of star that the James Webb Space Telescope will be looking for when it goes live in October 2018.
This is a digitized image of the oldest star in our galaxy. This aging starHD140283 is 190 light years away. The Hubble Space Telescope estimated its age at 14.5 billion plus or minus 800 million years.
The most striking star of all is HD 140283, informally called the Star of Methuselah. It is only 190 light years away and we can measure its brightness, surface temperature and composition; we can also see that it is just beginning to develop into a subgiant phase to become a red giant later on. These pieces of information allow us to derive a well-defined age for the star, and the result is troubling to say the least: 14.46 billion years. Some properties of the star, such as the iron content of 0.4% of the sun, say that the star is old, but not the oldest of all. And despite the possible error of 800 million years, Methuselah still creates a certain conflict between the maximum age of the stars and the age of the universe.
has not changed for billions of years. But as stars grow older, the most massive cease to exist, and the least massive begin to turn into subgiants.
Today it is obvious that something could have happened to this star in the past that we do not yet know today. Maybe she was born more massive and somehow lost her outer layers. It may be that the star absorbed some matter later, which changed its abundance of heavy elements, confusing our observations. Maybe we just don't understand the subgiant phase in the stellar evolution of ancient low-metallicity stars. Gradually, we will deduce the correct shape or calculate the age of the oldest stars.
But if we are right, we will face a serious problem. In our Universe, there cannot exist a star that will be older than the Universe itself. Either something is wrong with the estimate of the age of these stars, or something is wrong with the estimate of the age of the universe. Or something else that we do not yet understand at all. This is a great chance to move science in a new direction.
We live in a galaxy called the Milky Way, an empire of hundreds of billions of races. How did we get here? What awaits us in the future? These questions are inseparable from the concept of a galaxy. Our universe has two hundred billion galaxies, all of them are unique, huge and constantly changing. Where do galaxies originate from? How are they arranged? What is their future? And how will they die?
This is our Milky Way galaxy, about twelve billion years old. The galaxy is a giant disk with huge spiral arms and a glow in the center; there are an uncountable number of such galaxies in space. The galaxy is a large cluster of stars, on average it has a hundred billion stars. This is a real star incubator, a place where stars are born and where they die. Stars in a galaxy appear from clouds of dust and gas called nebulae. Our galaxy contains billions of stars, many of which are surrounded by planets and moons. For a long time we knew very little about galaxies, a hundred years ago mankind believed that the Milky Way was the only galaxy, scientists called it our island in the universe, other galaxies did not exist for them. But in 1924, astronomer Edwin Hubble changed the general idea, Hubble observed space with the most advanced telescope of its time with a lens diameter of 254 centimeters. In the night sky, he saw obscure clubs of light that were very far from us, the scientist came to the conclusion that these were not single stars, but entire star cities, galaxies far beyond the Milky Way.
Hubble made one of the greatest discoveries in astronomy: there is not one galaxy in space, but a great many galaxies. Our galaxy has a vortex structure, it has two spiral arms, and it has about one hundred and sixty million stars. Galaxy M-87 is a giant ellipse, one of the oldest galaxies in the universe, and the stars in it radiate golden light.
Galaxies are huge, real giants, on earth they measure distance in kilometers, in space astronomers use a unit of length, a light year, the distance traveled by light in one year, they are approximately equal to nine and a half trillion kilometers.
The Milky Way galaxy seems huge to us, but compared to other galaxies in the universe, it is quite small. Our nearest galactic neighbor, the Andromeda Nebula, is 200,000 light-years across, twice the size of our Milky Way. tiny. AC 1011 is 6,000,000 light-years across and is the largest known galaxy, 60 times the size of the Milky Way.
So, we know that galaxies are huge and they are everywhere, but where did they come from?. To create stars, gravity is needed, to unite stars into galaxies, it needs even more. The first stars appeared just 200,000,000 years after the big bang, then gravity pulled them together to form the first galaxies.
Galaxies have existed for more than twelve billion years, we know that these vast empires of stars take on a variety of forms from vortex spirals to huge balls of stars, but still much in galaxies remains a mystery to us.
Young galaxies are shapeless accumulations of stars of gas and dust, only after billions of years they turn into structures such as a vortex galaxy. The force of gravity gradually pulls the stars together, they rotate faster and faster until they take the form of a disk, then the stars and gas form giant spiral arms, this process was repeated in the vastness of space billions of times. Each galaxy is unique, but they all have one thing in common, they all revolve around their center. For years, scientists have wondered that it has enough power to change the behavior of the galaxy, and finally, the answer was found: a black hole and not just a black hole, but a super-massive black hole. Super massive black holes are fed by gas and stars, sometimes the black hole consumes them too greedily and the food is thrown back into space in the form of a beam of pure energy. The black hole at the center of the Milky Way is gigantic, 24,000,000 kilometers wide. The planet earth is located at a distance of twenty-five thousand light-years from the center of the Milky Way, which is many billions of kilometers. Super massive black holes can be a source of powerful gravity, but they do not have enough strength to keep the connection between the bodies of galaxies. By all the laws of physics, galaxies should disintegrate, why doesn't this happen? In space, there is a force more powerful than a super massive black hole, it cannot be seen and almost impossible to calculate, but it exists, it is called dark matter and it is everywhere. It seems that galaxies exist separately, there are trillions of kilometers between them, but in fact the galaxies are united in groups, a cluster of galaxies. Clusters of galaxies form superclusters that include tens of thousands of galaxies. Galaxies not only change, but also move, it happens that galaxies collide with each other and then one absorbs the other. The collision of galaxies lasts millions of years and in the end the two galaxies merge into one. Similar collisions occur in space everywhere, and our galaxy is no exception. Our galaxy is moving towards another galaxy, the Andromeda Nebula, and this does not bode well for our galaxy. The Milky Way is approaching Andromeda at 250,000 miles per hour, which means that in five to six billion years our galaxy will be gone. Oddly enough, when galaxies collide, the stars will not collide with each other, they are still too far apart, they will simply mix. However, the dust and gas between the stars will begin to heat up, at some point they will ignite, the two colliding galaxies will become white hot. The inhabitants of the planet "earth" are incredibly lucky, life originated on our planet only due to the fact that our solar system is in the right part of the galaxy, if we were a little closer to the center, we would not have survived.
Our galaxy and many other galaxies in the universe put before us a bunch of questions that need answers and secrets that have not yet been discovered by anyone. It is in galaxies that the key to understanding the universe lies.
Galaxies are born, crash, collide and die; galaxies are superstars for the world of science.
For many centuries, millions of human eyes, with the onset of night, direct their gaze upward - towards the mysterious lights in the sky - stars in our universe. Ancient people saw various figures of animals and people in clusters of stars, and each of them created their own history. Later, such clusters began to be called constellations. To date, astronomers identify 88 constellations that divide the starry sky into certain areas, by which you can navigate and determine the location of the stars. In our Universe, the most numerous objects accessible to the human eye are precisely the stars. They are the source of light and energy for the entire solar system. They also create the heavy elements necessary for the origin of life. And without the stars of the Universe there would be no life, because the Sun gives its energy to almost all living beings on Earth. It warms the surface of our planet, thus creating a warm, full of life oasis among the permafrost of space. The degree of brightness of a star in the universe is determined by its size.
Do you know the biggest star in the entire universe?
The star VY Canis Majoris, located in the constellation Canis Major, is the largest representative of the stellar world. It is currently the largest star in the universe. The star is located 5 thousand light years from the solar system. The diameter of the star is 2.9 billion km.
But not all stars in the universe are so huge. There are also so-called dwarf stars.
Comparative sizes of stars
Astronomers evaluate the magnitude of stars on a scale according to which the brighter the star, the lower its number. Each subsequent number corresponds to a star ten times less bright than the previous one. The brightest star in the night sky in the universe is Sirius. Its apparent magnitude is -1.46, which means it is 15 times brighter than a zero-magnitude star. Stars with a magnitude of 8 or more cannot be seen with the naked eye. Stars are also divided by color into spectral classes that indicate their temperature. There are the following classes of stars in the Universe: O, B, A, F, G, K, and M. Class O corresponds to the hottest stars in the Universe - blue. The coldest stars belong to the class M, their color is red.
| Class | Temperature, K | true color | Visible color | Main features |
|---|---|---|---|---|
| O | 30 000—60 000 | blue | blue | Weak lines of neutral hydrogen, helium, ionized helium, multiply ionized Si, C, N. |
| B | 10 000—30 000 | white-blue | white-blue and white | Absorption lines for helium and hydrogen. Weak H and K Ca II lines. |
| A | 7500—10 000 | white | white | Strong Balmer series, the H and K Ca II lines increase towards the F class. Metal lines also begin to appear closer to the F class. |
| F | 6000—7500 | yellow-white | white | The H and K lines of Ca II, metal lines are strong. The hydrogen lines begin to weaken. The Ca I line appears. The G band formed by the Fe, Ca, and Ti lines appears and intensifies. |
| G | 5000—6000 | yellow | yellow | The H and K lines of Ca II are intense. Ca I line and numerous metal lines. The hydrogen lines continue to weaken, and bands of CH and CN molecules appear. |
| K | 3500—5000 | orange | yellowish orange | The metal lines and the G band are intense. Hydrogen lines are almost invisible. TiO absorption bands appear. |
| M | 2000—3500 | red | orange red | The bands of TiO and other molecules are intense. The G band is weakening. Metal lines are still visible. |
Contrary to popular belief, it is worth noting that the stars of the universe do not actually twinkle. This is just an optical illusion - the result of atmospheric interference. A similar effect can be observed on a hot summer day, looking at hot asphalt or concrete. The hot air rises, and it seems as if you are looking through trembling glass. The same process causes the illusion of stellar twinkling. The closer a star is to Earth, the more it will "flicker" because its light travels through the denser layers of the atmosphere.
Nuclear Center of the stars of the Universe
A star in the universe is a giant nuclear focus. The nuclear reaction inside it converts hydrogen into helium through the process of fusion, so the star acquires its energy. Hydrogen atomic nuclei with one proton combine to form helium atoms with two protons. The nucleus of an ordinary hydrogen atom has only one proton. The two isotopes of hydrogen also contain one proton, but also have neutrons. Deuterium has one neutron, while Tritium has two. Deep inside a star, a deuterium atom combines with a tritium atom to form a helium atom and a free neutron. As a result of this long process, a huge amount of energy is released.
For main sequence stars, the main source of energy is nuclear reactions involving hydrogen: the proton-proton cycle, characteristic of stars with a mass near the solar one, and the CNO cycle, which occurs only in massive stars and only in the presence of carbon in their composition. In the later stages of a star's life, nuclear reactions can also take place with heavier elements, up to iron.
| Proton-proton cycle | CNO cycle | |
| Main chains |
|
|
When a star's hydrogen supply is depleted, it begins to convert helium into oxygen and carbon. If the star is massive enough, the transformation process will continue until carbon and oxygen form neon, sodium, magnesium, sulfur, and silicon. As a result, these elements are converted into calcium, iron, nickel, chromium and copper until the core is completely metal. As soon as this happens, the nuclear reaction will stop, since the melting point of iron is too high. The internal gravitational pressure becomes higher than the external pressure of the nuclear reaction and, eventually, the star collapses. Further development of events depends on the initial mass of the star.
Types of stars in the universe
The main sequence is the period of existence of the stars of the Universe, during which a nuclear reaction takes place inside it, which is the longest segment of the life of a star. Our Sun is currently in this period. At this time, the star undergoes minor fluctuations in brightness and temperature. The duration of this period depends on the mass of the star. In large massive stars it is shorter, while in small ones it is longer. Very large stars have enough internal fuel for several hundred thousand years, while small stars like the Sun will shine for billions of years. The largest stars turn into blue giants during the main sequence.
Types of stars in the universe |
|
| red giant- This is a large reddish or orange star. It represents the late stage of the cycle, when the supply of hydrogen comes to an end and helium begins to be converted into other elements. An increase in the internal temperature of the core leads to the collapse of the star. The outer surface of the star expands and cools, causing the star to turn red. Red giants are very large. Their size is a hundred times larger than ordinary stars. The largest of the giants turn into red supergiants. A star called Betelgeuse in the constellation Orion is the most striking example of a red supergiant. |  |
| white dwarf- this is what remains of an ordinary star after it passes the stage of a red giant. When a star runs out of fuel, it can release some of its matter into space, forming a planetary nebula. What remains is the dead core. A nuclear reaction is not possible in it. It shines due to its remaining energy, but sooner or later it ends, and then the core cools down, turning into a black dwarf. White dwarfs are very dense. They are no larger than the Earth in size, but their mass can be compared with the mass of the Sun. These are incredibly hot stars, reaching temperatures of 100,000 degrees or more. |  |
| brown dwarf also called a substar. During their life cycle, some protostars never reach critical mass to start nuclear processes. If the mass of a protostar is only 1/10 of the mass of the Sun, its radiance will be short-lived, after which it quickly fades. What remains is the brown dwarf. It's a massive ball of gas, too big to be a planet and too small to be a star. It is smaller than the Sun, but several times larger than Jupiter. Brown dwarfs emit neither light nor heat. This is just a dark clot of matter that exists in the vastness of the universe. |  |
| cepheid is a star with a variable luminosity, the pulsation cycle of which varies from a few seconds to several years, depending on the variety of the variable star. Cepheids usually change their luminosity at the beginning of life and at its end. They are internal (changing luminosity due to processes inside the star) and external, changing brightness due to external factors, such as the influence of the orbit of the nearest star. This is also called a dual system. |  |
| Many stars in the universe are part of large star systems. double stars- a system of two stars, gravitationally connected to each other. They revolve in closed orbits around a single center of mass. It has been proven that half of all the stars in our galaxy have a pair. Visually, paired stars look like two separate stars. They can be determined by the shift of the spectrum lines (Doppler effect). In eclipsing binaries, stars periodically outshine each other because their orbits are located at a small angle to the line of sight. |  |
Life Cycle of the Stars of the Universe
A star in the universe begins its life as a cloud of dust and gas called a nebula. The gravity of a nearby star or the blast wave of a supernova can cause the nebula to collapse. The elements of the gas cloud coalesce into a dense region called a protostar. As a result of the subsequent compression, the protostar heats up. As a result, it reaches a critical mass, and the nuclear process begins; gradually the star goes through all the phases of its existence. The first (nuclear) stage of a star's life is the longest and most stable. The lifespan of a star depends on its size. Large stars consume their life fuel faster. Their life cycle can last no more than a few hundred thousand years. But small stars live for many billions of years, as they spend their energy more slowly.
But be that as it may, sooner or later, stellar fuel runs out, and then a small star turns into a red giant, and a large star into a red supergiant. This phase will last until the fuel is completely used up. At this critical moment, the internal pressure of the nuclear reaction will weaken and no longer be able to balance the force of gravity, and, as a result, the star will collapse. Then the small stars of the Universe, as a rule, reincarnate into a planetary nebula with a bright shining core, called a white dwarf. Over time, it cools down, turning into a dark clot of matter - a black dwarf.
For big stars, things happen a little differently. During the collapse, they release an incredible amount of energy, and a powerful explosion gives birth to a supernova. If its magnitude is 1.4 the magnitude of the Sun, then, unfortunately, the core will not be able to maintain its existence and, after the next collapse, the supernova will become a neutron star. The internal matter of the star will shrink to such an extent that the atoms form a dense shell consisting of neutrons. If the stellar magnitude is three times greater than the solar value, then the collapse will simply destroy it, wipe it off the face of the Universe. All that remains of it is a site of strong gravity, nicknamed a black hole.
The nebula left behind by the star of the universe can expand over millions of years. In the end, it will be affected by the gravity of a nearby or the blast wave of a supernova and everything will repeat itself again. This process will take place throughout the universe - an endless cycle of life, death and rebirth. The result of this stellar evolution is the formation of heavy elements necessary for life. Our solar system came from the second or third generation of the nebula, and because of this, there are heavy elements on Earth and other planets. And this means that in each of us there are particles of stars. All the atoms of our body were born in an atomic hearth or as a result of a devastating supernova explosion.
.
Historical site of Bagheera - secrets of history, mysteries of the universe. Mysteries of great empires and ancient civilizations, the fate of disappeared treasures and biographies of people who changed the world, the secrets of special services. The history of wars, the mysteries of battles and battles, reconnaissance operations of the past and present. World traditions, modern life in Russia, the mysteries of the USSR, the main directions of culture and other related topics - all that official history is silent about.
Learn the secrets of history - it's interesting ...
Reading now
One day in 1722, Peter I personally cut symbolic wings from the white dress of his daughter Elizabeth. Sovereign Pyotr Alekseevich learned about this ritual in Europe and hurried to conduct it in his palace, especially since his child "passed" for twelve years. After the wings fell to the floor, Elizabeth began to be considered a bride. True, when the conversation turned to marriage in the family, Lizanka always began to cry and beg her parents to leave her at home.
Lenin argued that the NEP would lead the country out of the crisis, and Soviet power would only grow stronger, since all the levers of control would remain in the hands of the state. And the economy really took off, but the proletarian leader was slightly mistaken about the “leverage”.
Even in the harsh times of the Middle Ages, they tried not to execute sailors: it was too long and difficult to teach a good seaman. An experienced sailor was worth its weight in gold, which, however, did not prevent the ship's executioners (professors, executors - this position was called differently in the navies of different countries) in the era of sailboats to tear their servants like Sidorov's goats. But the death penalty for sailors was still quite rare. To do this, it was necessary to commit a truly terrible crime.
“Hearts made of strong damask steel” - this is how we usually talk about people, emphasizing their resilience. But do you know what bulat is? Do you remember that this word is inextricably linked with the history of Russia?
In the summer of 1941, Moscow was under martial law. The increasing frequency of German bomber raids forced the Soviet government to evacuate the most valuable archives, museum exhibits and cultural items from the capital. The mummy of V.I. Lenin.
In the heroic and tragic 30s of the 20th century, Russian women more than once demonstrated to the world their unbending fortitude and their achievements in professions previously unthinkable for women. In October 1938, TASS announced a new aviation world record for flight range. The heavy twin-engine aircraft "Rodina", controlled by a female crew consisting of: the first pilot - Valentina Grizodubova, the co-pilot - Polina Osipenko, the navigator - Marina Raskova, flew on the route Moscow - the Far East.
Almost 30 years have passed since the collapse of the Soviet Union, but the question "Who is to blame for the death of the red empire?" is still relevant. Some believe that communism was in itself an unviable utopia, others point to the "subversive activities of capitalist intelligence." However, very little attention is given to how another giant of Western civilization, the Roman Catholic Church, contributed to the fall of communist regimes almost all over the world.
Tanzania appeared on the map in 1964 as a result of the unification of two countries - Tanganyika and Zanzibar. Before that, the real laws of the jungle reigned here - it was a colony that supplied coffee, tobacco and slaves. And only in the middle of the 20th century the country needed new people. And there were such - the son of the tribal leader Julius Nyerere was in the right place at the right time.
Stars are huge balls of hot plasma. The size of some of them will amaze even the most unimpressive reader. So, are you ready to be amazed?
Below is a list of the ten largest (in diameter) stars in the universe. Let's make a reservation right away that this ten is made up of those stars that we already know. With a high degree of probability, in the vastness of our vast universe, there are luminaries with an even larger diameter. It is also worth noting that some of the presented celestial bodies belong to the class of variable stars, i.e. they periodically expand and contract. And finally, we emphasize that in astronomy all measurements have some error, so the numbers indicated here may differ slightly from the actual sizes of stars for such scales.
1. VY Canis Major
This red hypergiant has left all its competitors far behind. The radius of the star, according to various estimates, exceeds the solar one by 1800-2100 times. If VY Canis Major were the center of our solar system, its edge would come close to the orbit. This star is located about 4.9 thousand light years in the constellation Canis Major.
2. VV Cephei A
The star is located in the constellation Cepheus at a distance of about 2.4 thousand light years. This red hypergiant is 1600-1900 times larger than ours.
3. Mu Cephei
It is in the same constellation. This red supergiant is 1650 times larger than the Sun. In addition, Mu Cephei is one of the brightest stars. It is more than 38,000 times brighter than our star.
4. V838 Unicorn
This red variable star is located in the constellation Monoceros at a distance of 20 thousand light years from Earth. Perhaps it shone even more than VV Cephei A and Mu Cephei, but the huge distance separating the star from our planet does not allow at the moment to make more accurate calculations. Therefore, it is usually attributed to it from 1170 to 1970 solar radii.
5. WHO G64
It was previously thought that this red hypergiant could compete in size with VY Canis Major. However, it was recently revealed that this star from the constellation Dorado is only 1540 times larger than the Sun. The star is located outside the Milky Way in the dwarf galaxy Large Magellanic Cloud.
6. V354 Cephei
This red hypergiant is quite a bit inferior to WHO G64: it is 1520 times larger than the Sun. The star is relatively close, only 9 thousand light years from Earth in the constellation Cepheus.
7. KY Cygnus
This star is at least 1420 times larger than the Sun. But, according to some calculations, it could even top the list: the argument is serious - 2850 solar radii. However, the real dimensions of the celestial body are most likely close to the lower limit, which led the star to the seventh line of our rating. The luminary is located 5 thousand light years from Earth in the constellation Cygnus.
8. KW Sagittarius
Located in the constellation Sagittarius, the red supergiant is 1460 times the radius of the Sun.
9. RW Cephei
There are still disputes over the dimensions of the fourth representative of the constellation Cepheus. Its dimensions are about 1260-1650 solar radii.
10. Betelgeuse
This red supergiant is located just 640 light years from our planet in the constellation Orion. Its size is 1180 solar radii. Scientists believe that Betelgeuse can be reborn at any moment, and we will be able to observe this most interesting process practically "from the front rows."
The comparative sizes of the stars can be estimated from this video:
