The rarest star. The largest star in the Universe - UY Shield

The sun is not the most big 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 all matter in the solar system, and inside a star you can place a million planets like our Earth.

The one and only for the inhabitants of the Earth, the Sun is just one of the billions of billions of stars that are in our Milky Way galaxy and beyond - in the endless Universe. Some of these stars are really huge: they are clearly visible in the electromagnetic range and have a significant gravitational effect on the nearby celestial bodies that we can detect them, even if they are millions of light years 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 mass. 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 in their mass and magnitude are classified as hypergiants. Among the many hypergiants fixed on the vast expanses of the universe, three of them can be distinguished.

R136a1

The largest star will not always be the heaviest, and conversely, the heaviest star does not have to be the largest. This is easily proved by the star with 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 for this moment, while its radius is "only" 31 solar radius. The huge reserves of fuel 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, 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 Shield will not amaze you with its mass, which is 10 solar, but you will be surprised by it colossal size - about 1500 solar radii. The distance to UY Shield is 9500 light years, and at such a 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 have swallowed up all space, including the orbit of Jupiter along with the planet itself. The volume of this hypergiant is 5 billion times the volume of the Sun.


UY Shield in the constellation Shield |

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 through an ordinary amateur telescope, and in especially favorable conditions with the naked eye. By the way, if UY Shield was not surrounded by a large cloud of dust, then this star would be the fifth brightest object in the night sky, whereas now it is eleventh.

NML Swan

The star NML Swan is a true record holder with a radius of 1650 solar radius. During the pulsation of the 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.


Photo of a group of stars Swan OB2 | source

NML Cygnus, located in the constellation Cygnus at a distance of 5,300 light years from Earth, is the largest star currently known to astronomy. However, we can say with confidence that further space exploration will bring new discoveries and records.

Star - VY Big Dog is the largest known star in the Milky Way. A mention of her can be found in the star catalog, published back in 1801. There she is listed as a star of the seventh magnitude.

The red hypergiant VY Canis Majoris is 4,900 light-years from Earth. It is 2,100 times larger than the Sun. In other words, if we imagine that VY suddenly appeared in the place of our star, then it would swallow all the planets up to Saturn. It will take 1100 years to fly around such a "ball" at a speed of 900 km / h. However, when moving at the speed of light, it will take much less time - only 8 minutes.

Since the mid-19th century, VY of Canis Major has been known to have a crimson hue. It was assumed to be multiple. But later it turned out that this is a single star and has no companion. And the surrounding nebula provides a crimson spectrum of light.

3 or more stars that are seen as closely spaced are called multiples. If in fact they are just close to the line of sight, then this is an optically multiple star, if united by gravity - a physically multiple.

With such a gigantic size, the mass of the star is only 40 times the mass of the Sun. The density of gases inside it is very low - this explains such an impressive size and relatively low weight. The force of gravity is unable to prevent the loss of stellar fuel. It is believed that by now the hypergiant has already lost more than half of its original mass.

Back in the middle of the 19th century, scientists noted that the giant star was losing its brightness. However, this parameter is still very impressive - the brightness of the VY glow is 500 times higher than the Sun.

Scientists believe that when VY runs out of fuel, it will explode into a supernova. The explosion will destroy any life for several light years around. But the Earth will not suffer - the distance is too great.

And the smallest

In 2006, it appeared in the press that a group of Canadian scientists led by Dr. Harvey Reicher discovered the smallest currently known star in our galaxy. It is located in the star cluster NGC 6397 - the second farthest from the Sun. The studies were carried out using the Hubble telescope.

The mass of the discovered star is close to the theoretically calculated lower limit and is 8.3% of the mass of the Sun. The existence of smaller stellar objects is considered impossible. Their small size simply does not allow nuclear fusion reactions to start. The brightness of such objects is similar to the glow of a candle lit on the moon.

In fact, this question is not as simple as it seems. Determining the exact sizes of stars is very difficult, it is calculated based on a lot of indirect data, because we cannot see their disks directly. Direct observation of the stellar disk has so far been carried out only for a few large and close supergiants, and there are millions of stars in the sky. Therefore, it is not so easy to determine which is the largest star in the Universe - you have to rely mainly on the calculated data.

In addition, in some stars, the boundary between the surface and the huge atmosphere is very blurred, and where one ends and another begins is difficult to understand. But this is an error not for some hundreds, but for millions of kilometers.

Many stars do not have a strictly defined diameter, they pulsate, and become larger and smaller. And they can change their diameter very significantly.

Moreover, science does not stand still. More and more accurate measurements are being made, distances and other parameters are being refined, and some stars are unexpectedly much more interesting than they seemed. This also applies to sizes. Therefore, we will consider several candidates that belong to the largest stars in the Universe. Note that they are all not so far away in cosmic terms, and they are also the most big stars in the Galaxy.

A red hypergiant that claims to be the largest star in the universe. Alas, this is not so, but very close. It is in third place in size.

VV Cepheus - that is, double, and the giant in this system is component A, and we will talk about it. The second component is an unremarkable blue star, 8 times the size of the Sun. But the red hypergiant is also a pulsating star, with a period of 150 days. Its dimensions can vary from 1050 to 1900 times the diameter of the Sun, and at its maximum it shines 575,000 times brighter than our star!

This star is 5,000 light years away from us, and at the same time in the sky it has a brightness of 5.18 m, that is, with a clear sky and good vision, it can be found, and even with binoculars it is generally easy.

UY Shield

This red hypergiant is also striking in its size. Some sites mention it as the largest star in the universe. It belongs to semi-regular variables and pulsates, so the diameter can vary - from 1708 to 1900 solar diameters. Just imagine a star 1900 times larger than our Sun! If you place it in the center of the solar system, then all the planets, up to Jupiter, will be inside it.


Sun, Sirius, Pollux, Arcturus, against the background of the UY Shield. It is probably the largest star in the universe.

In numbers, the diameter of this one of the largest stars in space is 2.4 billion kilometers, or 15.9 astronomical units. 5 billion suns could fit inside it. It shines 340,000 times stronger than the Sun, although the surface temperature is much lower - due to its larger area.

At the peak of brightness UY Shield is visible as a faint reddish star with a brightness of 11.2 m, that is, it can be seen through a small telescope, but it is not visible to the naked eye. The fact is that the distance to this large star is 9500 light years - we would never see another on it. In addition, there are dust clouds between us - if they were not there, UY Shield would be one of the brightest stars in our sky, despite the great distance to it.

UY Shield is a huge star. She can be compared with the previous candidate - VV Cepheus. At the maximum, they are about the same, and it is not even clear which one is greater. However, there is definitely an even bigger star!

VY Big Dog

The diameter of VY, however, according to some data, is estimated at 1800-2100 solar, that is, it is a clear record among all other red hypergiants. If it were in the center of the solar system, it would have swallowed up all the planets, along with Saturn. Previous candidates for the title of the largest stars in the universe would also fit into it completely.

Light takes only 14.5 seconds to circle our Sun completely. The light would have had to fly 8.5 hours to go around VY Big Dog! If you were to make such a flyby along the surface in a fighter jet, at a speed of 4500 km / h, such a non-stop journey would take 220 years.


Comparison of the sizes of the Sun and VY Canis Major.

This star still raises a lot of questions, since its exact size is difficult to establish due to the diffuse corona, which has a much lower density than the solar one. And the star itself has a density thousands of times less than the density of the air we breathe.

In addition, VY of Canis Major is losing its substance and has formed a noticeable nebula around itself. This nebula may now have even more matter than the star itself. In addition, it is unstable, and in the next 100 thousand years it will explode as a hypernova. Fortunately, it is 3900 light years away, and the Earth is not threatened by this terrible explosion.

This star can be found in the sky with binoculars or a small telescope - its brightness varies from 6.5 to 9.6 m.

What is the largest star in the universe?

We looked at some of the largest stars in the universe known to scientists today. Their sizes are amazing. They are all candidates for this title, but the data is constantly changing - science does not stand still. According to some reports, UY Shield can also "swell" up to 2200 solar diameters, that is, it becomes even larger than VY Big Dog. On the other hand, there is too much controversy about the VY size of Canis Major. So these two stars are practically equal candidates for the title of the largest stars in the Universe.

Which of them turns out to be more in fact, will be shown by further research and clarifications. While the majority is inclined in favor of UY Shield, and you can safely call this star the largest in the Universe, it will be difficult to refute this statement.

Of course, talking about the whole Universe is not very correct. This is perhaps the largest star in our Milky Way galaxy known to scientists today. But since it has not yet been discovered yet larger, it is still the largest in the Universe.

Determining the largest star in the Universe, its size and mass has always been difficult for scientists. The angular dimensions of the stars are so small that even the largest telescopes cannot see stars in the form of round disks. Accordingly, the size of stars even with the largest telescope cannot be determined. Scientists have learned to determine the size of the most big stars based on the three most famous methods:

  • Observing the eclipse of the satellite of the earth - the Moon, scientists have learned to determine angular dimension, 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 the star by the formula L \u003d? T4 4? R2 or

This method allows you to find the radius of a star by its temperature and luminosity, since the parameters R, L and T are known.

What is a star?

Star - a luminous gas (plasma) celestial body formed from a gas-dusty environment in which thermonuclear reactions take place.

The sun is a typical G2 dwarf star with a radius of 696 thousand km.

The largest star belongs to the class of red hypergiants, although difficulties in determining the exact sizes of most stars lead to the fact that it is not possible to say with great certainty which star is the largest in the universe.

Red hypergiants are stars in their very last stages 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 envelope of very rarefied gas that surrounds the star's central core.

Hypergiants - these are stars of huge sizes and masses, having a luminosity class 0 in the Hertzsprung-Russell diagram (the diagram shows the relationship between the absolute stellar magnitude, spectral class, luminosity, and temperature of the star's surface), hypergiant stars are defined as the most powerful, heaviest, brightest and at the same time the rarest and short-lived supergiants.

What is the largest star in the universe?

The equatorial radius of the Sun, 695,500 km, is used as a unit for measuring the radius of stars.

As mentioned above, the exact size order of the largest stars is difficult to determine. many large stars have extended atmospheres and opaque dust envelopes and disks, or even pulsate.

In the very first place in some of the largest stars in the universe is a star VY Big Dog (lat.VY Canis Majoris, VY CMa). The distance from Earth to the largest star in the universe, VY Canis Major, is approximately 5,000 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 largest stars in space belongs to a star WOH G64located 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 Sonets.

In fourth place is the 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 times the radius of a star named the Sun.

The fifth place is taken 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. The radius is 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 Crowter, professor of astrophysics at the University of Sheffield, while studying a huge number of star clusters, discovered a star whose mass is much greater than the mass of the Sun.

Scientists have discovered several stars with surface temperatures in excess of 40,000 degrees. It is more than seven times hotter than the temperature on the Sun and several million times brighter. Some of these stars were born with masses over 150 solar masses.

The heaviest star, named R136a1, is from cluster RMC 136a (better known as R136), a cluster of young, massive and hottest stars located inside the Tarantula Nebula 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, with a luminosity 10 million times that of the Sun. The mass of R136a1 is 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 star. The star Proxima Centauri is a red dwarf 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 less 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 Sirius star 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 is 23 times that of the Sun. Initially, Sirius consisted of two of the most powerful blue stars of spectral class A, now the age of this binary star is about 230 million years.

The brightest star in the universe is Pollux in the constellation Gemini. Although it is very difficult to determine the brightest star. Also in the list of the brightest stars stars compete: Shaula (constellation Scorpio); Gakrux (constellation of the Southern Cross); Castor (in the constellation Gemini). Star Pistol (English Pistol Star) is one of the most bright stars in our Galaxy. The luminosity of the star Pistol exceeds 1.7 million luminosities of the Sun, i.e. in 20 seconds the star Pistol emits as much light as the sun emits in a whole year.

In our galaxy. This is associated with huge distances in space and the complexity of observations with the subsequent analysis of the data obtained. To date, scientists have managed to discover and register about 50 billion luminaries. More sophisticated technology allows you to explore distant corners of space and receive new information about objects.

Evaluation and search for supergiants in space

Modern astrophysics in the process of space exploration is constantly faced with a large number of questions. The reason for this is the gigantic size of the visible Universe, about fourteen billion light years. Sometimes, observing a star, it is quite difficult to estimate the distance to it. Therefore, before embarking on a journey in search of a definition of what is the largest star in our galaxy, it is necessary to understand the level of complexity of observing space objects.

Earlier, before the beginning of the twentieth century, it was believed that our galaxy is one. Visible other galaxies were classified as nebulae. But Edwin Hubble dealt a crushing blow to the ideas of the scientific world. He argued that there are many galaxies, and ours is not the largest.

The cosmos is incredibly huge

The distances to the nearest galaxies are enormous. Reach hundreds of millions of years. It is quite problematic for astrophysicists to determine which is the largest star in our galaxy.

Therefore, it is even more difficult to talk about other galaxies with trillions of stars, at a distance of one hundred million or more light years. In the process of research, new objects are discovered. The discovered stars are compared and the most unique and largest ones are determined.

Supergiant in the constellation of the Shield

The name of the largest star in our galaxy is UY Shield, a red supergiant. This is a variable which varies from 1700 to 2000 times the diameter of the Sun.

Our brains are incapable of imagining such quantities. Therefore, for a complete understanding of what size the largest star in the galaxy is, it is necessary to compare it with the values \u200b\u200bwe understand. For comparison, our solar system... The size of the star is so large that if it is placed in the place of our Sun, then the border of the supergiant will be in the orbit of Saturn.

And our planet and Mars will be inside the star. The distance to this "monster" of space is about 9600 light years.

The largest star in the galaxy - UY Shield - can only be conditionally considered a "king". The reasons are obvious. One of them is huge cosmic distances and cosmic dust, which make it difficult to obtain accurate data. Another problem is directly related to physical properties supergiants. With a diameter of 1,700 times larger than our celestial body, the largest star in our galaxy is only 7-10 times more massive than it. It turns out that the density of the supergiant is millions of times less than the air around us. Its density is comparable to that of the Earth's atmosphere at an altitude of about one hundred kilometers above sea level. Therefore, it is quite problematic to determine exactly where the boundaries of the star end and its "wind" begins.

At the moment, the largest star in our galaxy is at the end of its development cycle. It expanded (the same process will happen with our Sun at the end of evolution) and began active combustion of helium and a number of other elements heavier than hydrogen. A few million years later, the largest star in the galaxy - UY Shield - will turn into a yellow supergiant. And later - into a bright blue variable, and possibly into a Wolf-Rayet star.

Along with the "king" - the UY Shield supergiant - about ten stars with similar sizes can be noted. These include VY Canis Major, Cepheus A, NML Cygnus, WOH G64 VV and a number of others.

It is known that all the largest stars are short-lived and very unstable. Such stars can exist for both millions of years and several millennia, ending their life cycle in the form of a supernova or black hole.

The largest star in the galaxy: the search continues

Looking at the dramatic changes over the past twenty years, it is worthwhile to assume that over time, our understanding of the possible parameters of supergiants will differ from those previously known. And it is quite possible that in the coming years another supergiant will be discovered, with a greater mass or size. And new discoveries will push scientists to revise previously adopted dogmas and definitions.

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