Determining the largest star in the universe, its size and mass has always been not easy for scientists. The angular dimensions of the stars are so small that even the largest telescopes fail to see stars in the form of round disks. Accordingly, the sizes of stars even in the largest telescope cannot be determined. Scientists have learned to determine the size of the largest stars based on the three most famous methods:
- Observing the eclipse of the Earth's satellite - the Moon, scientists have learned to determine the angular size, and, knowing the distance to the object, you can determine its true, linear dimensions;
- The size of a star can be determined using special stellar optical interferometers. The principle of operation of these devices is based on the interference of starlight, which is reflected by a pair of widely spaced mirrors.
- The size of a star can also be calculated theoretically, based on estimates of the total luminosity and temperature of stars according to the Stefan–Boltzmann law. The luminosity of a star is related to the radius of a star by the formula L = ?T4 4?R2 or
This method allows you to find the radius of a star from its temperature and luminosity, since the parameters R , L and T are known.
What is a star?
Star - a luminous gaseous (plasma) celestial body formed from a gas-dust environment in which thermonuclear reactions take place.
The sun - a typical dwarf star of the spectral type G2, with a radius of 696 thousand km.
The largest star belongs to the class of red hypergiants, although the difficulty in determining the exact size of most stars means that it cannot be said with great certainty which star is the largest in the universe.
Red hypergiants are stars in the most recent stage of evolution. When the supply of hydrogen used as a source of nuclear energy in the central part of the star's core begins to deplete, a stage of internal changes begins, as a result of which the outer layers of the star expand greatly. The red hypergiant consists of a vast shell of very rarefied gas surrounding the central core of the star.
Hypergiants - these are stars of enormous size and mass, having on the Hertzsprung-Russell diagram (the diagram shows the relationship between the absolute stellar magnitude, spectral class, luminosity, and temperature of the surface of the star) luminosity class 0, hypergiant stars are defined as the most powerful, heaviest, brightest and at the same time the rarest and shortest-lived supergiants.
What is considered the largest star in the universe?
As a unit for measuring the radius of stars, the equatorial radius of the Sun is used - 695,500 km.
As mentioned above, it is difficult to determine the exact size order of the largest stars, because. many large stars have extended atmospheres and opaque dust shells and disks, or even pulsate.
In the very first place in a number of the largest stars in the universe is the star VY Canis Major(lat. VY Canis Majoris, VY CMa). The distance from Earth to the largest star in the universe VY Canis Majoris is approximately 5000 light years. The radius of the star was determined in 2005 and is in the range of 1800-2100 solar radii. The mass of the largest star is ~15-25 solar masses.
The second place of the largest stars in space belongs to the star WOH G64 located in the Large Magellanic Cloud galaxy. The radius is 1738 solar radii.
In third place is a large star VV Cephei A, with a radius of 1600-1900 radii of the Sun.
In fourth place is a star Mu Cephei(? Cep / ? Cephei), better known as Herschel's Garnet Star, is a red supergiant located in the constellation Cepheus. The radius of the star is 1650 radii of the star named Sun.
The fifth place is occupied by a star KY Swan- a star located in the constellation Cygnus at a distance of about 5153 light years from us. This is one of the largest stars known to science. Radius 1420 solar radii. 
The ratio of the sizes of the planets of the solar system and some well-known stars, including VY Canis Major:
1.Mercury
5. Aldebaran
6. Betelgeuse
What is the heaviest (massive) star in the universe?
On June 21, 2010, astronomers led by Paul Crowther, a professor of astrophysics at the University of Sheffield, while studying a huge number of star clusters, discovered a star with a mass much larger than the mass of the Sun.
Scientists have discovered several stars with surface temperatures in excess of 40,000 degrees. This is more than seven times hotter than the temperature of the Sun and several million times brighter. Some of these stars were born with masses greater than 150 solar masses.
The heaviest star has been named R136a1, from the RMC 136a cluster (better known as R136), a cluster of young, massive and hottest stars, located inside the Tarantula Nebula, located in the Large Magellanic Cloud, 165,000 light-years from planet Earth. The R136a1 star is one of the most powerful stars in the universe, 10 million times more luminous than the Sun. R136a1 has a mass of 265 solar masses and a radius of 67 solar radii.
What is the closest star to the solar system?
The closest star to Earth after the Sun is Proxima Centauri, which is 4.243±0.002 light-years from Earth, which is 270,000 times the distance from Earth to the Sun. Proxima Centauri is a red dwarf star orbiting the Alpha Centauri system.
The mass of Proxima Centauri is 0.123 ± 0.006 solar masses, which is 7 times less than the mass of the Sun and 150 times more than the mass of the planet Jupiter. Age 4.85?109 years. Temperature 3042 ± 117 K. Radius 0.145 ± 0.011 solar radii, i.e. the actual diameter is 7 times smaller than the diameter of the Sun's star and only 1.5 times the diameter of the planet Jupiter.
What is the brightest star in the night sky?
Sirius is the brightest star in the sky, from the constellation Canis Major. The star Sirius can be observed from almost any region of the Earth, with the exception of only its northernmost regions. Sirius is one of the closest stars to us and is only 8.6 light-years away from the solar system. The brightness of Sirius exceeds the brightness of the Sun by 23 times. Initially, Sirius consisted of two powerful blue stars of spectral class A, now the age of this double star is about 230 million years.
The brightest star in the universe is the star Pollux in the constellation Gemini. Although it is very difficult to determine the brightest star. Also in the list of the brightest stars, the following stars compete: Shaula (the constellation of Scorpio); Gacrux (constellation of the Southern Cross); Castor (in the constellation of Gemini). The Pistol Star is one of the brightest stars in our galaxy. The luminosity of the Pistol star exceeds 1.7 million luminosities of the Sun, i.е. in 20 seconds, the Pistol star emits as much light as the Sun emits in a whole year.
Seemingly inconspicuous UY Shield
Modern astrophysics in terms of stars seems to be re-experiencing its infancy. Observations of the stars give more questions than answers. Therefore, when asking which star is the largest in the Universe, you need to be immediately ready for answers. Are you asking about the largest star known to science, or about what limits science limits a star to? As is usually the case, in both cases you will not get a definitive answer. The most likely candidate for the largest star quite equally shares the palm with his "neighbors". As for how much it can be less than the real "king of the star" also remains open.
Comparison of the sizes of the Sun and the star UY Scuti. The sun is an almost invisible pixel to the left of UY Shield.
The supergiant UY Scutum, with some reservation, can be called the largest star observed today. Why "with reservation" will be said below. UY Scuti is 9500 light-years away and is seen as a dim variable star visible through a small telescope. According to astronomers, its radius exceeds 1700 radii of the Sun, and during the pulsation period this size can increase to as much as 2000.
It turns out that if such a star were placed in the place of the Sun, the current orbits of a terrestrial planet would be in the bowels of a supergiant, and the boundaries of its photosphere would sometimes rest against the orbit. If we imagine our Earth as a grain of buckwheat, and the Sun as a watermelon, then the diameter of the UY Shield will be comparable to the height of the Ostankino TV tower.
To fly around such a star at the speed of light will take as much as 7-8 hours. Recall that the light emitted by the Sun reaches our planet in just 8 minutes. If you fly at the same speed with which it makes one revolution around the Earth in an hour and a half, then the flight around the UY Shield will last almost five years. Now imagine these scales, given that the ISS flies 20 times faster than a bullet and tens of times faster than passenger airliners.
Mass and Luminosity of UY Shield
It is worth noting that such a monstrous size of the UY Shield is completely incomparable with its other parameters. This star is "only" 7-10 times more massive than the Sun. It turns out that the average density of this supergiant is almost a million times lower than the density of the air surrounding us! For comparison, the density of the Sun is one and a half times the density of water, and a grain of matter even “weighs” millions of tons. Roughly speaking, the averaged matter of such a star is similar in density to the layer of the atmosphere located at an altitude of about one hundred kilometers above sea level. This layer, also called the Karman line, is a conditional boundary between the earth's atmosphere and space. It turns out that the density of the UY Shield is only a little short of the vacuum of space!
Also UY Shield is not the brightest. With its own luminosity of 340,000 solar, it is ten times dimmer than the brightest stars. A good example is the star R136, which, being the most massive star known today (265 solar masses), is almost nine million times brighter than the Sun. At the same time, the star is only 36 times larger than the Sun. It turns out that R136 is 25 times brighter and about the same times more massive than UY Shield, despite the fact that it is 50 times smaller than the giant.
Physical parameters of the UY Shield
In general, UY Scuti is a pulsating variable red supergiant of spectral type M4Ia. That is, on the Hertzsprung-Russell spectrum-luminosity diagram, UY Scutum is located in the upper right corner.
At the moment, the star is approaching the final stages of its evolution. Like all supergiants, she began to actively burn helium and some other heavier elements. According to current models, in a matter of millions of years, UY Scutum will successively transform into a yellow supergiant, then into a bright blue variable or a Wolf-Rayet star. The final stages of its evolution will be a supernova explosion, during which the star will shed its shell, most likely leaving behind a neutron star.
Already now UY Scutum shows its activity in the form of semi-regular variability with an approximate pulsation period of 740 days. Given that a star can change its radius from 1700 to 2000 solar radii, the rate of its expansion and contraction is comparable to the speed of spaceships! Its mass loss is an impressive rate of 58 millionth solar masses per year (or 19 Earth masses per year). This is almost one and a half earth masses per month. So, being on the main sequence millions of years ago, UY Scutum could have had a mass of 25 to 40 solar masses.
Giants among the stars
Returning to the reservation mentioned above, we note that the primacy of UY Shield as the largest known star cannot be called unequivocal. The fact is that astronomers still cannot determine the distance to most stars with a sufficient degree of accuracy, and therefore estimate their size. In addition, large stars tend to be very unstable (recall the UY Scutum pulsation). Similarly, they have a rather blurry structure. They may have a fairly extended atmosphere, opaque gas and dust shells, disks, or a large companion star (an example is VV Cephei, see below). It is impossible to say exactly where the boundary of such stars passes. In the end, the well-established concept of the boundary of stars as the radius of their photosphere is already extremely arbitrary.
Therefore, this number can include about a dozen stars, which include NML Cygnus, VV Cepheus A, VY Canis Major, WOH G64 and some others. All these stars are located in the vicinity of our galaxy (including its satellites) and are in many ways similar to each other. All of them are red supergiants or hypergiants (see below for the difference between super and hyper). Each of them in a matter of millions, or even thousands of years, will turn into a supernova. They are also similar in size, ranging from 1400-2000 solar.
Each of these stars has its own peculiarity. So in UY Shield, this feature is the previously discussed variability. WOH G64 has a toroidal gas and dust envelope. Extremely interesting is the double eclipsing variable star VV Cephei. It is a close system of two stars, consisting of the red hypergiant VV Cephei A and the blue main sequence star VV Cephei B. The centers of these stars are located from each other in some 17-34 . Considering that the VV radius of Cepheus B can reach 9 AU. (1900 solar radii), the stars are located at "arm's length" from each other. Their tandem is so close that whole pieces of the hypergiant flow with great speeds to the “little neighbor”, which is almost 200 times smaller than it.
Looking for a leader
Under such conditions, estimating the size of stars is already problematic. How can one talk about the size of a star if its atmosphere flows into another star, or smoothly passes into a gas and dust disk? This is despite the fact that the star itself consists of a very rarefied gas.
Moreover, all the largest stars are extremely unstable and short-lived. Such stars can live for a few millions, or even hundreds of thousands of years. Therefore, observing a giant star in another galaxy, you can be sure that a neutron star is now pulsating in its place or a black hole is warping space, surrounded by the remnants of a supernova explosion. If such a star is even thousands of light years away from us, one cannot be completely sure that it still exists or has remained the same giant.
Add to this the imperfection of modern methods for determining the distance to stars and a number of unspecified problems. It turns out that even among the ten largest known stars, it is impossible to single out a certain leader and arrange them in ascending order of size. In this case, Shield's UY was cited as the most likely candidate to lead the Big Ten. This does not mean at all that its leadership is undeniable and that, for example, NML Cygnus or VY Canis Major cannot be larger than her. Therefore, different sources can answer the question about the largest known star in different ways. This speaks rather not about their incompetence, but about the fact that science cannot give unambiguous answers even to such direct questions.
The largest in the universe
If science does not undertake to single out the largest among the discovered stars, how can we say which star is the largest in the Universe? According to scientists, the number of stars even within the boundaries of the observable universe is ten times greater than the number of grains of sand on all the beaches of the world. Of course, even the most powerful modern telescopes can see an unimaginably smaller part of them. The fact that the largest stars can be distinguished by their luminosity will not help in the search for a “stellar leader”. Whatever their brightness is, it will fade when observing distant galaxies. Moreover, as noted earlier, the brightest stars are not the largest (an example is R136).
Also remember that when observing a large star in a distant galaxy, we will actually see its "ghost". Therefore, it is not easy to find the largest star in the Universe, its searches will be simply meaningless.
Hypergiants
If the largest star is impossible to find practically, maybe it is worth developing it theoretically? That is, to find a certain limit, after which the existence of a star can no longer be a star. Even here, however, modern science faces a problem. The current theoretical model of the evolution and physics of stars does not explain much of what actually exists and is observed in telescopes. An example of this is the hypergiants.
Astronomers have repeatedly had to raise the bar for the limit of stellar mass. This limit was first introduced in 1924 by the English astrophysicist Arthur Eddington. Having obtained the cubic dependence of the luminosity of stars on their mass. Eddington realized that a star cannot accumulate mass indefinitely. The brightness increases faster than the mass, and sooner or later this will lead to a violation of hydrostatic equilibrium. The light pressure of the increasing brightness will literally blow away the outer layers of the star. The limit calculated by Eddington was 65 solar masses. Subsequently, astrophysicists refined his calculations by adding unaccounted components to them and using powerful computers. So the modern theoretical limit for the mass of stars is 150 solar masses. Now remember that the mass of R136a1 is 265 solar masses, which is almost twice the theoretical limit!
R136a1 is the most massive star known today. In addition to it, several more stars have significant masses, the number of which in our galaxy can be counted on the fingers. Such stars are called hypergiants. Note that R136a1 is much smaller than the stars that, it would seem, should be below it in class - for example, the supergiant UY Shield. This is because hypergiants are called not the largest, but the most massive stars. For such stars, a separate class was created on the spectrum-luminosity diagram (O), located above the class of supergiants (Ia). The exact initial bar for the mass of a hypergiant has not been established, but, as a rule, their mass exceeds 100 solar masses. None of the biggest stars of the "Big Ten" falls short of these limits.
Theoretical impasse
Modern science cannot explain the nature of the existence of stars whose mass exceeds 150 solar masses. This raises the question of how a theoretical limit to the size of stars can be determined if the radius of a star, unlike mass, is itself a vague concept.
Let's take into account the fact that it is not known exactly what the stars of the first generation were, and what they will be in the course of the further evolution of the Universe. Changes in the composition, metallicity of stars can lead to radical changes in their structure. Astrophysicists have only to comprehend the surprises that will be presented to them by further observations and theoretical research. It is quite possible that UY Shield may turn out to be a real crumb against the background of a hypothetical "king-star" that shines somewhere or will shine in the farthest corners of our Universe.
Stars are large celestial bodies of hot plasma, the dimensions of which can amaze the most inquisitive reader. Ready to evolve?
It should be noted right away that the rating was compiled taking into account those giants that are already known to mankind. It is possible that somewhere in outer space there are stars of even larger dimensions, but it is located at a distance of many light years, and modern equipment is simply not enough to detect and analyze them. It is also worth adding that the largest stars will eventually cease to be such, because they belong to the class of variables. Well, do not forget about the probable errors of astrologers. So...
Top 10 biggest stars in the universe
10
Opens the rating of the largest stars in the Betelgeuse Galaxy, the size of which exceeds the radius of the sun by 1190 times. It is located approximately 640 light years from Earth. Comparing with other stars, we can say that at a relatively small distance from our planet. The red-colored giant in the next few hundred years can turn into a supernova. In this case, its dimensions will increase significantly. For justified reasons, the star Betelgeuse, ranking last in this ranking, is the most interesting!
RW
An amazing star, attracting with an unusual glow color. Its size exceeds the dimensions of the sun from 1200 to 1600 solar radii. Unfortunately, we cannot say exactly how powerful and bright this star is, because it is located far from our planet. Regarding the history of the emergence and distance of RW, leading astrologers from different countries have been arguing for many years. Everything is due to the fact that in the constellation it regularly changes. Over time, it may disappear altogether. But it is still in the top of the largest celestial bodies.
Next in the ranking of the largest known stars is KW Sagittarius. According to ancient Greek legend, she appeared after the death of Perseus and Andromeda. This suggests that it was possible to detect this constellation long before our appearance. But unlike our ancestors, we know about more reliable data. It is known that the size of the stars exceeds the Sun by 1470 times. However, it is relatively close to our planet. KW is a bright star that changes its temperature over time.
At present, it is known for certain that the size of this large star exceeds the size of the Sun by at least 1430 times, but it is difficult to get an accurate result, because it is located 5 thousand light years from the planet. Even 13 years ago, American scientists cite completely different data. At that time, it was believed that KY Cygnus had a radius that raised the Sun by 2850 times. Now we have more reliable dimensions relative to this celestial body, which, for sure, are more accurate. Based on the name, you understand that the star is located in the constellation Cygnus.
A very large star included in the constellation Cepheus is V354, the size of which exceeds the Sun by 1530 times. At the same time, the celestial body is relatively close to our planet, only 9 thousand light years away. It does not differ in special brightness and temperature against the background of other unique stars. However, it belongs to the number of variable luminaries, therefore, the dimensions may vary. It is likely that Cepheus will not last long at this position in the V354 rating. It will most likely decrease in size over time.
A few years ago, it was believed that this red giant could become a competitor for VY Canis Major. Moreover, some experts conditionally considered WHO G64 the largest known star in our Universe. Today, in an age of rapid development of technology, astrologers have managed to obtain more reliable data. It is now known that the radius of the Dorado is only 1550 times the size of the Sun. That's how huge errors are allowed in the field of astronomy. However, the incident is easily explained by distance. The star is outside the Milky Way. Namely, in a dwarf galaxy called the Huge Magellanic Cloud.
V838
One of the most unusual stars in the universe, located in the constellation of the Unicorn. It is located approximately 20 thousand light years from our planet. Even the fact that our specialists managed to find it is surprising. Luminary V838 is even larger than that of Mu Cephei. It is quite difficult to make accurate calculations regarding the dimensions, due to the huge distance from the Earth. Speaking of approximate size data, they range from 1170 to 1900 solar radii.
There are many amazing stars in the constellation Cepheus, and Mu Cephei is considered a confirmation of this. One of the largest stars exceeds the size of the Sun by 1660 times. The supergiant is considered one of the brightest in the Milky Way. Approximately 37,000 times more powerful than the illumination of the star most known to us, that is, the Sun. Unfortunately, we cannot say unequivocally at what distance from our planet Mu Cephei is located.
Myriads of stars dot the night sky. And to a person from Earth, they seem exactly the same. Well, in some parts of the sky, for example, in the Milky Way region, the stars merge into luminous streams.
This is because there is an incredibly huge number of stars in the universe.
In fact, there are so many of them that even the knowledge of modern researchers, which was obtained using the latest equipment (by the way, it allows you to look into space at 9 billion light years) is not enough.
Now there are about 50 billion stars in the depths of space. And every day the figure is only growing, because scientists do not get tired of exploring space and making new discoveries.
brighter than the sun
All stars in the universe have different diameters. And even our Sun is not the largest star, however, not a small one either. She has 1,391,000 kilometers in diameter. There are more significant stars in the Universe, they are called hypergiants. For a long time, VY, which is located in the constellation Canis Major, was considered the largest star. Not so long ago, the radius of the star was refined - and approximately ranges from 1300 to 1540 solar radii. The diameter of this supergiant is about 2 billion kilometers. VY is located 5 thousand light years from the solar system.
Scientists have calculated to imagine how gigantic it is, one revolution around the hypergiant star will take 1200 years, and then if you fly at a speed of 800 kilometers per hour. Or, if we reduce the Earth to 1 centimeter and also proportionally reduce VY, then the size of the latter will be 2.2 kilometers.
The mass of this star is not so impressive. VY is only 40 times heavier than the Sun. This happened because the density of gases inside it is incredibly low. Well, the brightness of the star can only be admired. It shines 500 thousand times stronger than our heavenly body.
The first observations of VY that were recorded are in the star catalog of Joseph Jérôme de Lalande. The information is dated March 7, 1801. Scientists pointed out that VY is a star of the seventh magnitude.
But in 1847, information appeared that VY had a crimson hue. In the nineteenth century, researchers discovered that the star has at least six discrete components, so it is likely a multiple star. But now it turned out that the discrete components are nothing more than bright patches of the nebula that surrounds the hypergiant. In 1957, visual observations and high-quality images from 1998 showed that VY was missing a companion star.
However, by our time, the largest star in the universe has already managed to lose more than half of its mass. That is, the star is aging and its hydrogen fuel is already running out. The outer part of VY has become larger due to the fact that gravity can no longer prevent weight loss. Scientists say that when a star runs out of fuel, it will most likely explode in a supernova and turn into a neutron star or a black hole. According to observations, the star has been losing its brightness since 1850.
Lost leadership
However, scientists do not leave the study of the Universe for a minute. Therefore, this record was broken. Astronomers have found an even bigger star in the vastness of space. The discovery was made by a group of British scientists led by Paul Crowther at the end of the summer of 2010.
The researchers studied the Large Magellanic Cloud and found the star R136a1. NASA's Hubble Space Telescope helped make an incredible discovery.
The giant in its mass is 256 times larger than our Sun. But in terms of brightness, R136a1 exceeds the celestial body by ten million times. Such fantastic figures were a revelation for scientists, because it was believed that stars that exceed the mass of the Sun by more than 150 times do not exist.
And continuing to explore the clusters of stars in the Large Magellanic Cloud, experts have found several more stars that have exceeded this milestone. Well, R136a1 turned out to be a real record holder. The most interesting thing is that throughout their existence, stars lose their mass. At least, such statements are made by scientists. And R136a1 has now lost one-fifth of its original mass. According to calculations, it was equal to 320 solar masses.
By the way, according to experts, if such a star is presented in our Galaxy, it would be brighter than the Sun as much as the Sun is brighter than the Moon.
Record-breaking stars
But the brightest in the visible sky are the stars Rigel and Deneb from the constellations Orion and Cygnus, respectively. Each shines brighter than the Sun 55 thousand times and 72.5 thousand times. These luminaries are removed from us by 1600 and 820 light years.
Another bright star from the constellation Orion is the star Betelgeuse. It is the third largest luminosity. It is brighter than sunlight by the strength of light emission by 22 thousand times. By the way, most of the brightest stars are collected in Orion, although their brightness changes periodically.
But the brightest among the stars closest to Earth is Sirius from the constellation Canis Major. It shines brighter than our Sun only 23.5 times. And the distance to this star is 8.6 light years. In the same constellation there is another bright star - Adara. This star shines like 8700 Suns combined at a distance of 650 light years. Well, the North Star, which many incorrectly consider the brightest visible star, shines 6 thousand times brighter than the Sun. The North Star is located at the tip of Ursa Minor and is 780 light years away from Earth.
If instead of the Sun there were other stars and planets
It is noteworthy that astronomers single out the zodiac constellation Taurus from the total mass. It contains an unusual star, which is distinguished by a supergiant density and a rather small spherical magnitude. According to astrophysicists, it mainly consists of fast neutrons that fly apart. It was once the brightest star in the universe.
Star R136a1 and the Sun
Big luminosity, scientists say, have blue stars. The brightest known is UW CMa. It is 860 thousand times brighter than our heavenly body. But this figure is rapidly falling, as the brightness of the stars changes over time. For example, according to the chronicle, which is dated July 4, 1054, the brightest star was in the constellation Taurus, it could be seen in the sky with the naked eye even in the middle of the day. But over time, the star began to fade and after a while it disappeared altogether. And in the place where she shone, a nebula formed, which looked like a crab. Hence the name Crab Nebula. It appeared after a supernova explosion. By the way, modern scientists have found a powerful source of radio emission in the center of this nebula, in other words, a pulsar. This is the remnant of that bright supernova, which was described in the old chronicle.
Subscribe to our channel in Yandex.Zen
The sun is not the biggest star in the universe. Compared to other stars, it can even be called small. But on the scale of our planet, the Sun is truly huge. Its diameter is 1.39 million km, it contains 99.86% of the entire matter of the solar system, and a million of the same planets as our Earth can be placed inside the star.
The only and unique for the inhabitants of the Earth, the Sun is just one of the billions of billions of stars located in our Milky Way galaxy, and beyond it - in the vast Universe. Some of these stars are really huge: they are clearly visible in the electromagnetic spectrum and have a significant gravitational effect on the nearest celestial bodies that we can detect them even if they are millions of light years away from our planet. Their dimensions are so large that a person is simply not able to imagine such a gigantic object, therefore they are measured not in kilometers, but in solar radii and solar masses. One solar radius is 696,342 km, and one solar mass is approximately 2,000,000,000,000,000,000,000,000,000,000 kg.
Stars that are significantly distinguished from others by their mass and size are classified as hypergiants. Among the many hypergiants recorded in the vast expanses of the universe, three of them can be especially distinguished.
R136a1
The largest star will not always be the heaviest, and vice versa, the heaviest star does not have to be the largest at all. This is easily proved by the star under the beautiful name R136a1. Located in the Large Magellanic Cloud at a distance of 165,000 light years from Earth, its mass is 265 solar masses, which is an absolute record at the moment, while its radius is "only" 31 solar radii. The huge fuel reserves inside this hypergiant and the extremely high density of matter allow R136a1 to emit 10 million times more light than the Sun, making it the brightest and most powerful star discovered to date. Scientists suggest that at the beginning of its life, this star could reach 320 solar masses, however, the stellar matter in the atmosphere of R136a1 accelerates more than the second cosmic velocity and overcomes the gravity of this celestial body, which generates a strong stellar wind, i.e. the outflow of stellar matter into interstellar space with a rapid loss of its mass.
UY Scutum will not amaze you with its mass, which is 10 solar radii, but you will be surprised by its colossal size - about 1500 solar radii. The distance to UY Scutum is 9500 light years, and at this distance it is difficult to say the exact radius of the star, but astronomers suggest that during pulsations it can increase to 2000 solar radii! If such a giant were placed in the center of the solar system, then it would swallow up all of space, including the orbit of Jupiter along with the planet itself. The volume of this hypergiant is 5 billion times greater than the volume of the Sun.
UY Scutum in the constellation Scutum | UY Shield is located at a distance of almost ten thousand light-years from the solar system, but due to the fact that the star is one of the brightest among those discovered, it can be easily seen from Earth with an ordinary amateur telescope, and in especially favorable conditions with the naked eye. By the way, if UY Scutum were not surrounded by a large cloud of dust, then this star would be the fifth brightest object in the night sky, while now it is the eleventh.
NML Cygnus
The star NML Cygnus is a real record holder with a radius equal to 1650 solar radii. During the pulsations of a star, the radius can reach about 2700 solar radii! If you place this hypergiant in the center of the solar system, then its photosphere will go far beyond the orbit of Jupiter, covering half the distance to Saturn.
Photograph of the Cygnus OB2 group of stars | a source The star NML Cygnus, located in the constellation Cygnus at a distance of 5300 light years from Earth, is the largest star known to astronomy at the moment. However, we can say with confidence that further exploration of space will bring new discoveries and records.
