Comparative monotony chemical composition famous celestial bodies will perhaps disappoint someone. However, there is no doubt that this fact is of great importance, confirming the material unity of the Cosmos. This unity gives us the right to extend to the stellar Universe the laws of nature that we have learned from experience within the modest confines of our Earth. All this is one of the clearest confirmations of the correctness of the dialectical-materialist worldview.
3. Lot in the abysses of the universe
Outside the solar system, such a large leap in distances has to be made to the stars that it was only possible a century ago, long after doubts about the similarity between the Sun and the stars had disappeared. The sea depth meter, - lot, in the field of astronomy, was repeatedly “thrown” in the direction of different stars and for a long time could not reach any of them, could not reach the “bottom”. This, of course, is only a figurative comparison, because, as in the case of determining the temperatures of luminaries, the possibility of direct measurements of distances is excluded here. As we will now see, they can only be found indirectly, calculated based on measurements of other quantities. This path, indicated by Copernicus, consists of measuring angles, but instruments and methods to achieve the necessary accuracy were created only in the second half of the 19th century.
As when determining the distance to any inaccessible object, the idea of the method is to measure the difference in the directions in which the star is visible from the two ends of a basis of known length. The distance corresponding to this difference in direction can be calculated using trigonometry. In this case, the diameter of the Earth as a basis turned out to be too small, and for the vast majority of stars, with the modern accuracy of measuring angles, even the diameter of the Earth's orbit is insufficient. Nevertheless, it was precisely this that Copernicus recommended to take as a basis, which was carried out by scientists of later generations.
Only a century ago, the remarkable astronomer V. Ya. Struve in Russia, Bessel in Germany and Henderson in South Africa managed to make fairly accurate measurements and for the first time establish the distances to some stars. The feeling experienced by contemporaries was reminiscent of the joy of sailors who, during a long voyage, unsuccessfully threw a lot and finally reached the bottom.
The classic way to determine distances to stars is to accurately determine the direction to them (i.e., to determine their coordinates on the celestial sphere) from two ends of the diameter of the earth's orbit. To do this, they need to be determined at moments separated from each other by six months, since during this time the Earth itself carries an observer with it from one side of its orbit to the other.
The apparent displacement of the star, caused by a change in the observer's position in space, is extremely small, barely perceptible. They prefer to measure it from a photograph, taking, for example, two photographs of the chosen star and its neighbors on the same plate, one photograph six months after the other. Most stars are so far away that their displacement in the sky is completely unnoticeable, but in relation to them a fairly close star moves noticeably. This is its displacement and is measured with an accuracy of 0",01 - greater accuracy has not yet been achieved, but it is already much higher than the accuracy achieved half a century ago.
The described apparent displacement of the star is twice the angle at which the radius of the earth's orbit would be visible from it and which is called the annual parallax.
Rice. 1. Parallax and proper motion of stars. In the figure, the parallax p of two stars close to each other and their proper motions μ are the same, but their path in space is different.
The parallax of these stars is the largest and amounts to 3/4"; it is measured with an accuracy of about 1%, since the accuracy of angular measurements reaches 0",01.
At an angle of about 0",01, the diameter of a penny appears to us if it is placed on its edge on Red Square in Moscow and viewed from Tula or Ryazan! This is the accuracy of astronomical measurements! At an angle of 0",01, to be precise, a ruler is visible, which is viewed at right angles from a distance 20,626,500 times greater than the length of the ruler.
It is easy to find out the corresponding distance by parallax. We get the distance to the star in the radii of the Earth's orbit if we divide the number 206,265 by the parallax value, expressed in arcseconds. To express it in kilometers, you need to multiply the resulting number by another 150,000,000.
We already know that it is more convenient to express large distances in light years or in parsecs, and Centauri and its neighbor, nicknamed “Nearest”, since it is still a little closer to us, are 270,000 times farther from us than the Sun, i.e. 4 light years. A courier train, traveling non-stop at a speed of 100 km per hour, would reach it in 40 million years! Try to take comfort in the memory of this if you ever get tired of a long train ride...
An accuracy of measuring parallaxes of 0.01 does not allow measuring parallaxes that are themselves less than this value, so the described method is not applicable to stars further than 300-350 light years away.
Using the described method and others using spectra, as well as using completely different indirect methods, it is possible to determine the distances to stars located much further than 300 light years. The light from the stars of some distant star systems reaches us hundreds of millions of light years away. This does not mean at all, as is often thought, that we are observing stars that may no longer exist in reality. It is not worth saying that “we see in the sky something that in reality no longer exists,” because the vast majority of stars change so slowly that millions of years ago they were the same as they are now, and even their visible places in the sky change extremely slowly, although stars move quickly in space.
This paradox arises from the fact that, in contrast to the wandering luminaries - planets, the stars of the constellations were once called motionless. Meanwhile, nothing can be stationary in the world. Two and a half centuries ago, Halley discovered the movement of Sirius across the sky. To notice a systematic change in the celestial coordinates of stars, their movement in the sky relative to each other, it is necessary to compare the exact determinations of their positions in the sky made over a period of tens of years. They are invisible to the naked eye, and throughout the history of mankind not a single constellation has noticeably changed its outline.
For most stars, no movement can be detected because they are too far from us. The horseman galloping along the quarry on the horizon, as it seems to us, almost stands still, and the turtle crawling at our feet moves quite quickly. So it is in the case of stars - we more easily notice the movements of the stars closest to us. Photos of the sky, which are convenient to compare with each other, help us a lot with this. Observations of the positions of stars in the sky were made long before the invention of photography, hundreds and even thousands of years ago. Unfortunately, they were too inaccurate for the movement of the stars to be seen from comparison with modern ones.
Conclusion
At first glance, the starry sky may even seem monotonous to the naked eye. Identical sparkling dots, randomly scattered across a dark background, and that’s it! But look at the starry sky again and again. After just a few sessions of close observation, the first “sorting” begins. You discover that stars can be large - dazzlingly brilliant and small - barely noticeable dots. It was this difference in the apparent brightness of stars that made it possible to introduce their first classification back in ancient times. Legends attribute the idea to Hipparchus. As if he suggested calling the brightest points stars of the first magnitude, and the weakest ones, barely visible to the naked eye, stars of the sixth magnitude. Stellar magnitudes are conventional units that characterize the apparent brightness, or, as experts say, the apparent brightness of stars. At first, stellar magnitudes were integers and were designated in order of decreasing brightness . But with the invention of telescopes, and then cameras and instruments that measure the smallest fractions of illumination, the scale of stellar magnitudes had to be expanded, intermediate - fractional - values had to be introduced, and for especially bright celestial objects - zero and negative stellar magnitudes. In these relative units, they began to measure the visible brightness of not only stars, but also the Sun, Moon and all planets.
To form your own opinion about apparent stellar magnitudes, you can offer a simple experiment. On a dark, moonless night, go somewhere away from the street lights and find the Dipper, part of the constellation Ursa Major.
Take a close look at the second star from the end of the Bucket handle. This is Mizar, a star of approximately second magnitude. But it's not her that interests us. Near good eyes should be able to spot a small fifth magnitude star called Alcor. Even during the time of Alexander the Great, Alcor served as a standard for testing the vision of legionnaires. The recruit was taken out into the field and forced to find a faintly glowing Alcor. Found it - good vision, good! If you don't find it, go home!
Today you will learn about the most unusual stars. It is estimated that there are about 100 billion galaxies in the Universe and about 100 billion stars in each galaxy. With so many stars, there are bound to be some strange ones among them. Many of the sparkling, burning balls of gas are quite similar to each other, but some stand out for their strange size, weight and behavior. Using modern telescopes, scientists continue to study these stars to better understand them and the Universe, but mysteries still remain. Curious to know about the strangest stars? Here are the 25 most unusual stars in the Universe.
25. UY Scuti
Considered a supergiant star, UY Scuti is so large that it could engulf our star, half of our neighboring planets, and virtually our entire solar system. Its radius is approximately 1700 times the radius of the Sun.
24. Star of Methuselah
Photo: commons.wikimedia.org
The Star of Methuselah, also named HD 140283, truly lives up to its name. Some believe it is 16 billion years old, which is a problem since the Big Bang only happened 13.8 billion years ago. Astronomers have tried to use more advanced age determination methods to better date the star, but still believe it is at least 14 billion years old.
23. Torna-Zhitkova object
Photo: Wikipedia Commons.com
The existence of this object was originally proposed theoretically by Kip Thorne and Anna Zytkow; it consists of two stars, a neutron and a red supergiant, combined into one star. A potential candidate for this object has been named HV 2112.
22.R136a1 
Photo: flickr
Although UY Scuti is the most big star, known to man, R136a1 is definitely one of the heaviest in the Universe. Its mass is 265 times greater than the mass of our Sun. What makes it strange is that we don't know exactly how it was formed. The main theory is that it was formed by the merger of several stars.
21.PSR B1257+12
Photo: en.wikipedia.org
Most of the exoplanets in PSR B1257+12's solar system are dead and bathed in deadly radiation from their old star. Amazing fact about their star is a zombie star or pulsar that has died but the core still remains. The radiation emanating from it makes this solar system a no man's land.
20.SAO 206462
Photo: flickr
Comprised of two spiral arms spanning 14 million miles across, SAO 206462 is certainly a strange and unique star in the universe. While some galaxies are known to have arms, stars typically do not. Scientists believe that this star is in the process of creating planets.
19. 2MASS J0523-1403
Photo: Wikipedia Commons.com
2MASS J0523-1403, perhaps the smallest famous star in the Universe, and it is only 40 light years away. Because it is small in size and mass, scientists believe it may be 12 trillion years old.
18. Heavy metal subdwarfs
Photo: ommons.wikimedia.org
Recently, astronomers discovered a pair of stars with large amounts of lead in their atmosphere, which creates thick and heavy clouds around the star. They're called HE 2359-2844 and HE 1256-2738, and they're located 800 and 1000 light-years away respectively, but you could just call them heavy metal subdwarfs. Scientists are still not sure how they form.
17. RX J1856.5-3754
Photo: Wikipedia Commons.com
From the moment they are born, neutron stars begin to continuously lose energy and cool down. It is therefore unusual that a 100,000-year-old neutron star such as RX J1856.5-3754 could be so hot and show no signs of activity. Scientists believe that interstellar material is held by the star's strong gravitational field, resulting in enough energy to heat the star.
16. KIC 8462852
Photo: Wikipedia Commons.com
The star system KIC 8462852 has received intense attention and interest from SETI and astronomers for its unusual behavior recently. Sometimes it dims by 20 percent, which could mean something is orbiting around it. Of course, this led some to the conclusion that these were aliens, but another explanation is the debris of a comet that entered the same orbit with the star.
15. Vega
Photo: Wikipedia Commons.com
Vega is the fifth brightest star in the night sky, but that's not what makes it strange. Its high rotation speed of 960,600 km per hour gives it an egg shape, rather than a spherical shape like our Sun. There are also temperature variations, with colder temperatures at the equator.
14. SGR 0418+5729
Photo: commons.wikimedia.org
A magnet located 6,500 light-years from Earth, SGR 0418+5729 has the strongest magnetic field in the Universe. What's strange about it is that it doesn't fit the mold of traditional magnetars, which have a surface magnetic field like regular neutron stars.
13. Kepler-47
Photo: Wikipedia Commons.com
In the constellation Cygnus, 4,900 light-years from Earth, astronomers have discovered for the first time a pair of planets orbiting two stars. Known as the Kelper-47 system, the orbiting stars eclipse each other every 7.5 days. One star is roughly the size of our Sun, but only 84 percent as bright. The discovery proves that there may be more than one planet in the stressed orbit of a binary star system.
12. La Superba
Photo: commons.wikimedia.org
La Superba is another massive star located 800 light years away. It is about 3 times heavier than our Sun and the size of four astronomical units. It is so bright that it can be observed from Earth with the naked eye.
11. MY Camelopardalis
Photo: commons.wikimedia.org
MY Camelopardalis was thought to be a lone bright star, but the two stars were later discovered to be so close that they practically touch each other. Two stars slowly join together to form one star. Nobody knows when they will completely merge.
10.PSR J1719-1438b
Photo: Wikipedia Commons.com
Technically, PSR J1719-1438b is not a star, but it once was. While it was still a star, its outer layers were sucked out by another star, turning it into a small planet. What's even more surprising about this former star, what is now a giant diamond planet, five times the size of Earth.
9. OGLE TR-122b
Photo: Photo: commons.wikimedia.org
The average star usually makes the other planets look like pebbles, but OGLE TR-122b is about the same size as Jupiter. That's right, this is the smallest star in the Universe. Scientists believe it originated as a stellar dwarf several billion years ago, marking the first time a star the size of a planet has been discovered.
8. L1448 IRS3B
Photo: commons.wikimedia.org
Astronomers discovered the three-star system L1448 IRS3B as it began to form. Using the ALMA telescope in Chile, they observed two young stars orbiting a much older star. They believe that these two young stars were the result of nuclear reaction with gas rotating around the star.
Photo: Wikipedia Commons.com
Mira, also known as Omicron Ceti, is 420 light-years away and is quite strange due to its constantly fluctuating brightness. Scientists consider it a dying star, in the last years of its life. Even more amazingly, it moves through space at a speed of 130 km per second and has a tail that stretches several light years.
6. Fomalhaut-C
Photo: Wikipedia Commons.com
If you thought the two-star system was cool, then you might want to see the Fomalhaut-C. This is a three-star system just 25 light-years from Earth. While triple star systems are not entirely unique, this one is because the location of the stars far away rather than close to each other is an anomaly. The star Fomalhaut-C is particularly far away from A and B.
5. Swift J1644+57
Photo: Wikipedia Commons.com
The black hole's appetite is indiscriminate. In the case of Swift J1644+57, a dormant black hole woke up and devoured the star. Scientists made this discovery in 2011 using X-ray and radio waves. It took 3.9 billion light years for the light to reach Earth.
4.PSR J1841-0500
Photo: Wikipedia Commons.com
Known for their regular and constantly pulsating glow, they are rapidly rotating stars that rarely turn off. But PSR J1841-0500 surprised scientists by only doing this for 580 days. Scientists believe that studying this star will help them understand how pulsars work.
3.PSR J1748-2446
Photo: Wikipedia Commons.com
The strangest thing about PSR J1748-2446 is that it is the fastest spinning object in the Universe. It has a density 50 trillion times that of lead. To top it all off, its magnetic field is a trillion times stronger than that of our Sun. In short, this is an insanely overactive star.
2. SDSS J090745.0+024507
Photo: Wikipedia Commons.com
SDSS J090745.0+024507 is a ridiculously long name for a runaway star. With the help of a supermassive black hole, the star has been knocked out of its orbit and is moving fast enough to escape the Milky Way. Let's hope that none of these stars rush towards us.
1. Magnetar SGR 1806-20
Photo: Wikipedia Commons.com
Magnetar SGR 1806-20 is a terrifying force that exists in our Universe. Astronomers detected a bright flash 50,000 light-years away that was so powerful it bounced off the Moon and illuminated Earth's atmosphere for ten seconds. The solar flare has raised questions among scientists about whether something similar could lead to the extinction of all life on Earth.
10
10th place - AH Scorpio
The tenth place of the largest stars in our Universe is occupied by the red supergiant, located in the constellation Scorpio. The equatorial radius of this star is 1287 - 1535 radii of our Sun. Located approximately 12,000 light years from Earth.
9
9th place - KY Lebed
The ninth place is occupied by a star located in the constellation Cygnus at a distance of approximately 5 thousand light years from Earth. The equatorial radius of this star is 1420 solar radii. However, its mass exceeds the mass of the Sun by only 25 times. KY Cygni shines about a million times brighter than the Sun.
8
8th place - VV Cepheus A
VV Cephei is an Algol-type eclipsing double star in the constellation Cepheus, which is located about 5,000 light-years from Earth. In the Milky Way Galaxy it is the second largest star (after VY Canis Majoris). The equatorial radius of this star is 1050 - 1900 solar radii.
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7th place - VY Canis Major
The largest star in our Galaxy. The radius of the star lies in the range 1300 - 1540 radii of the Sun. It would take light 8 hours to circle the star. Research has shown that the star is unstable. Astronomers predict that VY Canis Major will explode as a hypernova in the next 100 thousand years. Theoretically, a hypernova explosion would cause gamma-ray bursts that could damage the contents of a local part of the Universe, destroying any cellular life within a radius of several light years, however, the hypergiant is not close enough to Earth to pose a threat (about 4 thousand light years).
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6th place - VX Sagittarius
A giant pulsating variable star. Its volume, as well as its temperature, change periodically. According to astronomers, the equatorial radius of this star is equal to 1520 radii of the Sun. The star got its name from the name of the constellation in which it is located. The manifestations of the star due to its pulsation resemble the biorhythms of the human heart.
5
5th place - Westerland 1-26
The fifth place is occupied by a red supergiant, the radius of this star lies in the range 1520 - 1540 solar radii. It is located 11,500 light years from Earth. If Westerland 1-26 were at the center of the solar system, its photosphere would encompass the orbit of Jupiter. For example, the typical depth of the photosphere for the Sun is 300 km.
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4th place - WOH G64
WOH G64 is a red supergiant star located in the constellation Doradus. Located in the neighboring galaxy Large Magellanic Cloud. The distance to the solar system is approximately 163,000 light years. The radius of the star lies in the range 1540 - 1730 solar radii. The star will end its existence and go supernova in a few thousand or tens of thousands of years.
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3rd place - RW Cepheus
Bronze goes to the star RW Cephei. The red supergiant is located 2,739 light-years away. The equatorial radius of this star is 1636 solar radii.
2
2nd place - NML Lebed
The second largest star in the Universe is occupied by the red hypergiant in the constellation Cygnus. The radius of the star is approximately equal to 1650 solar radii. The distance to it is estimated at about 5300 light years. Astronomers discovered substances such as water, carbon monoxide, hydrogen sulfide, and sulfur oxide in the star's composition.
1
1st place - UY Shield
The largest star in our Universe at the moment is a hypergiant in the constellation Scutum. Located at a distance of 9500 light years from the Sun. The equatorial radius of the star is 1708 radii of our Sun. The star's luminosity is approximately 120,000 times greater than the luminosity of the Sun in the visible part of the spectrum, and would be much brighter if there were not a large accumulation of gas and dust around the star.
We live in a galaxy called the Milky Way, an empire consisting of hundreds of billions of people. How did we get here? What does the future hold for us? These questions are inseparable from the concept of a galaxy. Our universe contains two hundred billion galaxies, all of them are unique, huge and constantly changing. Where do galaxies come from? How are they built? 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 countless such galaxies in space. The galaxy is a large cluster of stars, on average it numbers a hundred billion stars. This is a real stellar incubator, a place where stars are born and where they die. Stars in a galaxy emerge 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, humanity 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 using the most advanced telescope of his time with a lens diameter of 254 centimeters. In the night sky, he saw unclear clouds of light that were very far from us, the scientist came to the conclusion that these were not individual stars, but entire star cities, galaxies far beyond the Milky Way.
Hubble made one of the greatest discoveries in astronomy: there is not just 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; it is one of the oldest galaxies in the universe and the stars in it emit golden light.
Galaxies are huge, real giants, on earth distances are measured 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 closest galactic neighbor, the Andromeda Nebula, reaches a diameter of 200,000 light years, twice the size of our Milky Way. M 87 is the largest galaxy in nearby space, it is much larger than Andromeda, but compared to the giant AC 1011, it seems completely tiny. AC 1011 is 6,000,000 light years wide and is the largest known galaxy, 60 times larger than the Milky Way.
So, we know that galaxies are huge and they are everywhere, but where did they come from? To create stars you need gravity, to unite stars into galaxies you need even more. The first stars appeared just 200,000,000 years after the big bang, then gravity pulled them together and the first galaxies appeared.
Galaxies have existed for more than twelve billion years, we know that these vast empires of stars host the most different shapes from vortex spirals to huge balls of stars, but still much in galaxies remains a mystery to us.
Young galaxies are formless accumulations of gas and dust stars; only after billions of years do 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 has been repeated billions of times in the vastness of space. Each galaxy is unique, but they all have one thing in common: they all revolve around their center. For years, scientists wondered what had enough power to change the behavior of a 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 feed on gas and stars, sometimes the black hole consumes them too greedily and the food is thrown back into space as a beam of pure energy. The black hole at the center of the Milky Way is gigantic, 24,000,000 kilometers wide. 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. Supermassive black holes can be a source of powerful gravity, but they do not have enough strength to maintain the connection between the bodies of galaxies. According to all the laws of physics, galaxies should decay, why doesn’t this happen? There is a force in space that is more powerful than a super massive black hole, it cannot be seen and is almost impossible to calculate, but it exists, it is called dark matter and it is everywhere. It seems that the galaxies exist separately, there are trillions of kilometers between them, but in fact the galaxies are united into groups, a cluster of galaxies. Clusters of galaxies form superclusters containing 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 eventually two galaxies merge into one. Similar collisions occur everywhere in space, 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 a speed of 250,000 miles per hour, which means that in five to six billion years our galaxy will no longer exist. Oddly enough, when galaxies collide, the stars will not collide with each other; they are still too far from each other; they will simply get mixed up. However, the dust and gas between the stars will begin to heat up, at some point they will ignite, and the two colliding galaxies will become white hot. The inhabitants of planet “earth” are incredibly lucky; life arose on our planet only thanks to the fact that our solar system is in the right part of the galaxy; if we were located a little closer to the center, we would not have survived.
Our galaxy and many other galaxies in the universe pose before us a bunch of questions that require 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, break up, collide and die; galaxies are superstars for the world of science.
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 about 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.
This leaves only one reasonable possibility: we must be misestimating the ages 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.
Extremely old stars can be found in globular clusters
Many of them are in globular clusters, which, to be 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, straining established cosmological models, but gradually improving understanding of stellar evolution has brought these numbers into line with the norm. We have developed more advanced techniques to improve our observational abilities, by measuring not only 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 4,140 light years away that contains only 1/20,000th the heaviest 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 mass of the Sun, contains just 0.1% of 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 the James Webb Space Telescope will be looking for when it starts operating 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 clarified its age at 14.5 billion plus or minus 800 million years
The most striking star of all is HD 140283, informally nicknamed the Star of Methuselah. It's only 190 light-years away, and we can measure its brightness, surface temperature, and composition; we can also see that it is just starting to develop into a subgiant phase to become a red giant. These pieces of information allow us to deduce a well-defined age for the star, and the result is worrying to say the least: 14.46 billion years. Some properties of the star, such as its iron content of 0.4% of the Sun, indicate 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 stars and the age of the Universe.
has not changed for billions of years. But as stars grow older, the most massive ones cease to exist, and the least massive ones 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. Maybe the star absorbed some material later that changed its heavy element content, confusing our observations. It may be that we simply have a poor understanding of the subgiant phase in the stellar evolution of ancient low metallicity stars. Gradually we will derive the correct form or calculate the age of the oldest stars.
But if we are right, we face a serious problem. There cannot be a star in our Universe that is older than the Universe itself. Either there is something 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 don’t understand at all yet. This is a great chance to move science in a new direction.
