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. So far, direct observation of the stellar disk has 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 not all that far away in cosmic terms, and they are also the largest 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. In terms of size, it is in third place.
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 diameters 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. Inside it could fit 5 billion suns. 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 of the Shield, it 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 not have seen another on it at all. 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 sources, 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 swallow 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 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, then 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 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 will explode into a hypernova in the next 100 thousand years. 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. All of them are candidates for this title, but the data is constantly changing - science does not stand still. According to some reports, the UY of the Shield can also "swell" up to 2200 solar diameters, that is, it becomes even larger than the VY of Canis Major. 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 entire 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 even larger, it is still the largest in the Universe.
> The largest star in the universe
UY Shield is the largest star in the Universe: description and characteristics of a star with a photo, location in the constellation, distance from Earth, a list of the largest stars.
It's easy to feel tiny when looking at the night sky. You just need to select an object for comparison. How about a star? Just look into the territory of the constellation Shield and you will find the largest star in our galaxy and the visible Universe - UY Shield.
In 1860, the star was found by German scientists at the Bonn Observatory. But only in 2012 was it possible to conduct a survey in the Very Large Telescope (Atacama Desert). Since its discovery, it is the largest star in size, surpassing Betelgeuse, VY Canis Major and NML Swan.
Of course, there are record holders for brightness and density, but UY Shield has the largest total size with a radius of 1,054,378,000 - 1,321,450,000 miles, which is 1,700 times the solar one.
It seems to people that the Earth is huge. But let's take an 8-inch ball. Then, in scale, the Sun will be 73 feet in diameter, which exceeds the height of the White House. Now let's put the UY of the Shield next to it and get a diameter of 125,000 feet.
What happens if you put the UY Shield in a sunny position? The star will dine on the first five planets and go beyond Jupiter's orbital path. But many people think that it can even cross the line of Saturn's orbit.
Well, let's be glad that the star is still not located in the solar system and is 9,500 light years distant.
It is important to emphasize that with the improvement of terrestrial instruments, we are discovering new objects that are distant at great distances. This means that one day we may bump into an even larger star.
It is worth noting that the largest known stars are represented here, since many objects remain outside the field of view. Also, some of the named ones act as variables, which means they are constantly shrinking and expanding. Now you know which is the largest star in space. Let's look at the rest of the top ten the largest stars in the Universe:
List of the largest stars in the universe
The red supergiant VY Canis Major has a radius of 1800-2100 solar, making it the largest in the galaxy. If put in place, it would cover the orbital path. It is 3900 light years distant towards the constellation Canis Major.
It is a red supergiant 1000 times the solar radius. Located 6,000 light years away. Represented by a binary system, where the main star is followed by a small blue.
Mu Cephei
Mu Cephei is a red supergiant with a radius of 1,650 times that of the Sun and 38,000 times brighter.
V 838 Unicorn is a red variable star 20,000 light years distant. It can reach the size of Mu Cephei or VV Cephei A, but the large distance makes it difficult to determine accurately. The range covers 380-1970 solar radii.
A red supergiant that is 1540 times larger than the solar radius. Located in the constellation Dorado.
V354 Cephei
A red supergiant that exceeds the solar radius by 1520 times. It is 9,000 light years distant towards the constellation Cepheus.
KY Swan
1420 times the solar radius, although some estimates put the figure at 2850 times. The star is 5,000 light years away and has not yet been able to get a clear image.
KW Sagittarius
The red supergiant is 1,460 times larger in radius than the Sun. Located 7800 light years away.
RW Cephei
A red supergiant with a radius of 1600 solar. From the position of the Sun could reach the orbital path of Jupiter.
A red supergiant with a radius 1000 times that of the Sun. It is the most popular star as it is located fairly close (640 light years) to. At any moment, it can transform into a supernova.
In our galaxy. This is associated with huge distances in space and the complexity of observations with subsequent analysis of the data obtained. To date, scientists have managed to discover and register about 50 billion luminaries. More advanced technology allows you to explore distant corners of space and receive new information about objects.
Assessment 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 notions 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 and more million 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 we understand. Our solar system is suitable for comparison. 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 the physical properties of supergiants. With a diameter of 1700 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 occur with our Sun at the end of evolution) and began active combustion of helium and a number of other elements heavier than hydrogen. After a few million years, 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.
All the largest stars are known to be short-lived and highly unstable. Such stars can exist for both millions of years and several millennia, ending their life cycle in the form of a supernova or a 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.
A myriad 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, stars merge into luminous streams.
This is because there is an incredible number of stars in the universe.
In fact, there are so many of them that even the knowledge of modern researchers, which was obtained with the help of the latest equipment (by the way, it allows you to look into the territory of space for 9 billion light years) is not enough.
There are now about 50 billion stars in the bowels 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, and not small. It has 1,391,000 kilometers in diameter. There are more weighty stars in the Universe, they are called hypergiants. For a long time, VY was considered the largest star, which is located in the constellation Canis Major. 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 a 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 decrease VY, then the size of the latter will be 2.2 kilometers.
The mass of this star is not that 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 VY observations that were recorded are in the star catalog of Joseph Jerome de Lalande. The information is dated March 7, 1801. Scientists have indicated that VY is a seventh magnitude star.
But in 1847, information appeared that VY has 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 areas of the nebula that surrounds the hypergiant. In 1957, visual observations and quality images from 1998 showed that VY lacks a companion star.
However, by our time the largest star in the universe has already lost 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 the star's fuel dries up, it is likely to explode in a supernova and turn into a neutron star or black hole. The star has been observed to lose 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 larger star in the vastness of space. The discovery was made by a group of British scientists led by Paul Crowther in the late 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 is 256 times more massive than our Sun. But the brightness of R136a1 exceeds the celestial body by ten million times. Such fantastic numbers became a revelation for scientists, because it was believed that stars that exceed the mass of the Sun by more than 150 times did 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 limit. Well, R136a1 turned out to be a real record holder. The most interesting thing is that throughout their entire 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 the calculations of experts, if such a star is imagined in our Galaxy, it would be brighter than the Sun as much as the Sun is brighter than the Moon.
Record 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 stars are removed from us by 1600 and 820 light years.
Another bright star from the constellation Orion is the star Betelgeuse. It has the third highest luminosity. It is 22 thousand times brighter than sunlight in terms of light intensity. By the way, most of the bright 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 just like 8,700 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. Polaris is located at the tip of the Ursa Minor and is 780 light-years distant from Earth.
If instead of the Sun there were other stars and planets
It is noteworthy that astronomers distinguish the zodiacal 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 scatter to the sides. It was once the brightest star in the universe.
Star R136a1 and the Sun
Blue stars have a high luminosity, scientists say. The brightest known is UW CMa. It is 860 thousand times brighter than our heavenly body. But this figure is falling rapidly, as the brightness of the stars changes over time. For example, according to the chronicle, which is dated July 4, 1054, in the constellation Taurus there was the brightest star, 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 it shone, a nebula formed that looked like a crab. This is how the name Crab Nebula appeared. She appeared after a supernova explosion. By the way, modern scientists in the center of this nebula have found a powerful source of radio emission, in other words, a pulsar. This is the remnant of that bright supernova that was described in the ancient chronicle.
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5.VV Cephei A
The fifth position in our rating went to the binary star VV Cepheus A, which has a radius of 1050-1900 solar. It is located in the constellation Cepheus. The luminary itself is an Algol-type eclipsing variable. Such objects are characterized by the presence of a cooler star passing in front of a hotter one. So some of the light from the hotter object is eclipsed and the overall brilliance of the vapor is temporarily reduced. VV Cephei is located at a distance of 5 thousand light years from us. The binary star consists of VV Cephei A (a red hypergiant with a radius of 1050 solar) and VV Cephei B, which is a blue B0 main sequence star. It revolves around VV Cephei A in an elliptical orbit.
The red hypergiant has a mass of about 25–100 solar masses. VV Cepheus A is at least the seventh largest star known to science. It also holds the honorable second place when it comes to the Milky Way galaxy specifically. In general, such luminaries (meaning hypergiants) are considered the most powerful, heaviest and brightest of the supergiants. Moreover, they are extremely rare. As for the "companion", this star is ten times larger than our Sun in diameter, and the luminosity index is 100,000 times higher.
VV Cepheus A and the Sun / © Reddit
4.VY Big Dog
On the fourth position of the rating is VY Canis Major, which is located in the constellation Canis Major. Before us is a hypergiant. The distance from us to VY Canis Major is 3900 light years, so it is not a fact that humanity will ever be able to investigate this object in detail. If we talk about the size, then the radius of the star is up to 1540 solar radii. There is another version, according to which we have an ordinary red supergiant, whose radius does not exceed 600 solar. In general, disputes about the size continue, although there is no doubt that we have a real "monster" in front of us. To imagine its size, let's give an example: if you imagine an aircraft with a speed of 4.5 thousand km / h, then it will take about 160 years for VY to fly around Canis Major.
With such monstrous dimensions, the mass of the star is only seventeen solar. This indicates the extremely low density of the star. Scientists believe that its explosion could occur within the next 100 thousand years. This threatens a cataclysm to the systems located nearby, but the Earth, according to scientists, will not be affected by this cataclysm.
VY Big Dog / © Wikipedia
And here is another red supergiant located in a nearby galaxy called the Large Magellanic Cloud. The latter is a dwarf galaxy of the SBm type and a companion of the Milky Way. The star WOH G64 is extremely distant from us - it is located at a distance of 163 thousand light years from the solar system. The lower limit of the star's radius is 1540 solar, the upper one - 1730. WOH G64 is probably not the largest star of all, but it firmly ranks first in terms of size when it comes to the luminaries of the Large Magellanic Cloud.
It was suggested that the luminosity of WOH G64 is 500 thousand solar with a mass 40 times greater than that of our star. Meanwhile, these data cannot be correlated with the low temperature of WOH G64, which is 3200 K. Subsequent observations showed that the luminosity of the star is reduced by dust and gas around it. Be that as it may, this star is huge: if it were placed in the center of our system, then the surface of WOH G64 would reach the orbit of Saturn - the sixth planet from the Sun.
The stellar wind led to the fact that the giant luminary lost up to a third of its entire mass. Within a few thousand years, it can turn into a supernova. True, this does not threaten the Earth: the star is located at an incredibly large distance from our planet.
A giant torus around WOH G64 / © ESO
UY Shita is a bright red supergiant of spectral type M4Ia. It is located in the constellation Shield. It is classified as a semi-regular variable star with an approximate pulsation period of 740 days. First of all, this star is interesting for its size, which allows it to gain a foothold in the second line of the rating of the largest stars. If we draw an analogy with our Sun, then the volume of the UY Shield is about 5 billion times larger. In this case, the radius of the star can be 1900 solar.
Assuming there is no light pollution, the UY of the Shield can be viewed using an ordinary small telescope or even binoculars. Is it a reddish star located 2 ° north of the naked-eye type-A star? Shield and 2 minutes arc northwest of the Eagle Nebula. And although when infrared radiation is taken into account, the brightness of the star exceeds the brightness of the Sun by 340 thousand times, this object "hides" behind a huge layer of dust and gas around it. UY Shield is also notable for being the fastest burning star. It loses an amount of mass equal to 5.8 · 10? 5 M? /year.
UY Shield / © Spacegid
1. NML Swan
And the deserved first place in our rating rightfully goes to the red hypergiant NML Swan. It is located in the constellation Cygnus (northern hemisphere of the starry sky). Its radius can reach 2775 solar! However, there is also a lower limit - in this case, the figure is approximately 1640 solar radii. The distance to the star is 5.3 thousand light years. The giant's mass is equal to 25-40 solar, and the luminosity exceeds that of our native star by 270 thousand times. NML Cygnus is distinguished by extremely high mass loss rates, which amount to 2 × 10 × 4 solar masses per year.
The star was discovered in 1965. Later it turned out that it contains silicon monoxide, carbon monoxide, hydrogen cyanide, carbon monosulfide, sulfur oxide, sulfur dioxide, hydrogen sulfide. However, the giant luminary continues to hide its secrets, and it will be possible to find answers to many questions only many years later.
Star Association, which houses NML Swan / © Wikimedia
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