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What is the biggest star? The smallest and largest star in our galaxy

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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.

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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.

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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 Galaxy Milky Way 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.

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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 in the center solar system, its photosphere would cover 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.

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2nd place - NML Lebed

The second place of the largest stars 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.

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1st place - UY Shield

The largest star in our Universe is at the moment- 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.

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

By 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, it is possible to determine its true, linear dimensions;
You can determine the size of a star using special stellar optical interferometers. The operating principle 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 = ?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 gas (plasma) celestial body formed from a gas-dust environment in which thermonuclear reactions occur.

Sun - a typical dwarf star of spectral class G2, with a radius of 696 thousand km.

The largest star is a red hypergiant, although the difficulty of determining the exact size of most stars means that it is impossible to say with much certainty which star is the largest in the universe.

Red hypergiants are stars in the very last stages of evolution. When the supply of hydrogen used as a source 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 greatly expand. A red hypergiant star consists of a vast shell of very tenuous gas surrounding the central core of the star.

Hypergiants - these are stars of enormous size and mass, having a luminosity class of 0 on the Hertzsprung-Russell diagram (the diagram shows the relationship between absolute stellar magnitude, spectral class, luminosity, and surface temperature of the star), hypergiant stars are defined as the most powerful, heaviest, brightest and at the same time the rarest and shortest-lived supergiants.

Which star is considered the largest in the universe?

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

As mentioned above, the exact order of sizes of the largest stars is difficult to determine, because many large stars have extensive 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 Majoris(lat. VY Canis Majoris, VY CMa). The distance from Earth to the largest star in the universe, VY Canis Majoris, 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 star 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 Sontz.

In fourth place is the star Mu Cephei(? Cep / ? Cephei), better known as Herschel's Garnet Star, is a red supergiant star located in the constellation Cepheus. The radius of the star is 1650 radii of the star called the Sun.

Star takes fifth place 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 Majoris:

1.Mercury

5.Aldebaran

6.Betelgeuse

What is the heaviest (massive) star in the Universe?

On June 21, 2010, astronomers led by Paul Crowther, professor of astrophysics at the University of Sheffield, while studying a huge number of star clusters, discovered a star whose mass greatly exceeds the mass of the Sun.

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

The heaviest star was 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, with a luminosity 10 million times greater 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. The star 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 star Sun 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 stars closest 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. Sirius originally 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 competing in the list of the brightest stars are the following stars: Shaula (constellation Scorpio); Gacrux (constellation of the Southern Cross); Castor (in the constellation 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.e. in 20 seconds, the Pistol star emits as much light as the Sun emits in a whole year.

What is the biggest star in the Universe?

Life on our entire planet depends on the Sun, and sometimes we don't realize that there are actually many other galaxies in and within the Universe. And our almighty Sun is just a small star among billions of other luminaries. Our article will tell you the name of the largest star in the world that can still be grasped by the human mind. Perhaps beyond its borders, in hitherto unexplored worlds, there exist even more gigantic stars of immense size...

Measure stars in Suns

Before we talk about the name of the largest star, let us clarify that the size of stars is usually measured in solar radii; its size is 696,392 kilometers. Many of the stars in our galaxy are in many ways larger than the Sun. Most of them belong to the class of red supergiants - large massive stars with a dense hot core and a rarefied envelope. Their temperature is noticeably lower than the temperature of blue ones - 8000-30,000 K (on the Kelvin scale) and 2000-5000 K, respectively. Red stars are called cold, although in fact their temperature is slightly lower than the maximum in the core of our Earth (6000 K).

Most celestial objects do not have constant parameters (including size), but rather are in constant change. Such stars are called variables - their sizes change regularly. This can happen for various reasons. Some variable stars are actually a system of several bodies exchanging mass, others pulsate due to internal physical processes, contracting and expanding again.

What is the name of the largest star in the Universe?

At a distance of 9.5 thousand light years from the Sun it appears on star maps in late XVII century, thanks to the Polish astronomer Jan Hevelius. And two hundred years later, German astronomers from the Bonn Observatory added the star UY Scuti (U-Igrek) to the catalog. And already in our time, in 2012, it was established that UY Scuti is the largest known star within the studied Universe.

The radius of UY Scuti is about 1700 times greater than the radius of the Sun. This red hypergiant is a variable star, which means its size can reach even larger values. During periods of maximum expansion, the radius of the UY Scutum is 1900 solar radii. The volume of this star can be compared to a sphere, the radius of which would be the distance from the center of the Solar system to Jupiter.

Giants of the Cosmos: what are the largest stars called?

The neighboring galaxy, the Large Magellanic Cloud, is home to the second largest star in space studied. Its name cannot be called particularly memorable - WOH G64, but you can take note that it is located in the constellation Doradus, constantly visible in the southern hemisphere. It is slightly smaller in size than UY Scutum - about 1500 solar radii. But it has an interesting shape - the accumulation of a rarefied shell around the core forms a spherical shape, but rather resembles a donut or bagel. Scientifically, this shape is called a torus.

According to another version, as the largest star after UY Scutum is called, VY Canis Majoris is in the lead. It is believed that its radius is 1420 solar. But the surface of VY Canis Majoris is too rarefied - the Earth’s atmosphere is several thousand times denser than it. Due to difficulties in determining what is the actual surface of the star and what is its accompanying shell, scientists cannot come to a final conclusion regarding the size of VY Canis Majoris.

The heaviest stars

If we consider not the radius, but the mass celestial body, then the largest star is called as a set of letters and numbers in encryption - R136a1. It is also located in the Large Magellanic Cloud, but belongs to the type blue stars. Its mass corresponds to 315 solar masses. For comparison, the mass of UY Scuti is only 7-10 solar masses.

Another massive formation is called Eta Carinae - a double giant star in the 19th century, as a result of an explosion around this system, a nebula was formed, named Homunculus because of its strange shape. The mass of Eta Carinae is 150-250 solar masses.

The largest stars in the night sky

Hiding in the depths of space, giant stars are inaccessible to the eye of the common man - most often they can only be seen through a telescope. At night, in the starry sky, the brightest objects closest to the Earth - be they stars or planets - will appear large to us.

What is the name of the largest star in the sky and at the same time the brightest? This is Sirius, which is one of the stars closest to Earth. In fact, in size and mass it is not particularly larger than the Sun - only one and a half to two times. But its brightness is really much greater - 22 times greater than that of the Sun.

Another bright and therefore seemingly large object in the night sky is actually not a star, but a planet. We are talking about Venus, whose brightness is in many ways superior to other stars. Its shine is visible closer to sunrise or some time after sunset.

The seemingly inconspicuous UY Shield

Modern astrophysics, in terms of stars, seems to be reliving its infancy. Star observations provide more questions than answers. Therefore, when asking which star is the largest in the Universe, you need to be immediately prepared for answering questions. Are you asking about the largest star known to science, or about what limits science limits a star? As is usually the case, in both cases you will not get a clear answer. The most likely candidate for the biggest star quite equally shares the palm with its “neighbors.” How much smaller it may be 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 Scutum.

With some reservations, the supergiant UY Scuti can be called the largest star observed today. Why “with reservation” will be stated below. UY Scuti is 9,500 light-years away from us and is observed as a faint variable star, visible in a small telescope. According to astronomers, its radius exceeds 1,700 solar radii, and during the pulsation period this size can increase to as much as 2,000.

It turns out, place such a star in the place of the Sun, the current orbits of the planet terrestrial group would find themselves in the depths of a supergiant, and the boundaries of its photosphere would at times abut 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 it will take as much as 7-8 hours. Let us remember that the light emitted by the Sun reaches our planet in just 8 minutes. If you fly at the same speed as it makes one revolution around the Earth in an hour and a half, then the flight around UY Scuti will last about 36 years. Now let’s imagine these scales, taking into account that the ISS flies 20 times faster than a bullet and tens of times faster than passenger airliners.

Mass and luminosity of UY Scuti

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 around us! For comparison, the density of the Sun is one and a half times higher than 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 a layer of atmosphere located at an altitude of about one hundred kilometers above sea level. This layer, also called the Karman line, is the conventional boundary between earth's atmosphere and space. It turns out that the density of the UY Shield is only slightly short of the vacuum of space!

Also UY Scutum is not the brightest. With its own luminosity of 340,000 solar, it is tens of times dimmer than the brightest stars. A good example is the star R136, which, being the most massive of the currently known stars (265 solar masses), is almost nine million times brighter than the Sun. Moreover, the star is only 36 times larger than the Sun. It turns out that R136 is 25 times brighter and about the same number of times more massive than UY Scuti, despite the fact that it is 50 times smaller than the giant.

Physical parameters of UY Shield

Overall, UY Scuti is a pulsating variable red supergiant of spectral class M4Ia. That is, on the Hertzsprung-Russell spectrum-luminosity diagram, UY Scuti is located in the upper right corner.

At the moment, the star is approaching the final stages of its evolution. Like all supergiants, it began actively burning helium and some other heavier elements. According to modern models, in a matter of millions of years, UY Scuti will successively transform into a yellow supergiant, then into a bright blue variable or Wolf-Rayet star. Final stages its evolution will be a supernova explosion, during which the star will throw off its shell, most likely leaving behind a neutron star.

Already now, UY Scuti is showing its activity in the form of semi-regular variability with an approximate pulsation period of 740 days. Considering that a star can change its radius from 1700 to 2000 solar radii, the speed of its expansion and contraction is comparable to the speed spaceships! Its mass loss is at an impressive rate of 58 million solar masses per year (or 19 Earth masses per year). This is almost one and a half Earth masses per month. Thus, being on the main sequence millions of years ago, UY Scuti could have had a mass of 25 to 40 solar masses.

Giants among the stars

Returning to the disclaimer stated above, we note that the primacy of UY Scuti as the largest known star cannot be called unambiguous. The fact is that astronomers still cannot determine the distance to most stars with a sufficient degree of accuracy, and therefore estimate their sizes. In addition, large stars are usually very unstable (remember the pulsation of UY Scuti). Likewise, they have a rather blurred structure. They may have a fairly extensive atmosphere, opaque shells of gas and dust, disks, or a large companion star (for example, VV Cephei, see below). It is impossible to say exactly where the boundary of such stars lies. After all, the 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 Cephei A, VY Canis Majoris, 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 will turn into a supernova in a few millions, or even thousands of years. They are also similar in size, lying in the range of 1400-2000 solar.

Each of these stars has its own peculiarity. So in UY Scutum this feature is the previously mentioned variability. WOH G64 has a toroidal gas-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 centra of these stars are located from each other at some 17-34 . Considering that the radius of VV 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 at enormous speeds onto 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 we talk about the size of a star if its atmosphere flows into another star, or smoothly turns into a disk of gas and dust? This is despite the fact that the star itself consists of 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, when 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 bending space, surrounded by the remnants of a supernova explosion. Even if such a star is thousands of light years away from us, one cannot be completely sure that it still exists or remains the same giant.

Let's add to this imperfection modern methods determining the distance to the stars and a number of unspecified problems. It turns out that even among a dozen known largest stars it is impossible to identify a specific leader and arrange them in order of increasing size. In this case, UY Shield was cited as the most likely candidate to lead the Big Ten. This does not mean at all that his leadership is undeniable and that, for example, NML Cygnus or VY Canis Majoris cannot be greater than her. Therefore, different sources may answer the question about the largest known star in different ways. This speaks less of their incompetence than of the fact that science cannot give unambiguous answers even to such direct questions.

Largest in the Universe

If science does not undertake to single out the largest among the discovered stars, how can we talk about which star is the largest in the Universe? Scientists estimate that the number of stars, even within 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 portion of them. It will not help in the search for a “stellar leader” that the largest stars can stand out for their luminosity. Whatever their brightness, it will fade when observing distant galaxies. Moreover, as noted earlier, the brightest stars are not the largest (for example, R136).

Let us 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; searching for it will simply be pointless.

Hypergiants

If the biggest star It’s impossible to find practically, maybe it’s worth developing it theoretically? That is, to find a certain limit after which the existence of a star can no longer be a star. However, even here modern science faces a problem. The modern theoretical model of evolution and physics of stars does not explain much of what actually exists and is observed in telescopes. An example of this is 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 a 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 this will sooner or later lead to a violation of hydrostatic equilibrium. The light pressure of 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 and using powerful computers. So the current theoretical limit for the mass of stars is 150 solar masses. Now remember that R136a1 has a mass of 265 solar masses, which is almost twice the theoretical limit!

R136a1 is the most massive star currently known. In addition to it, several other stars have significant masses, the number of which in our galaxy can be counted on one hand. Such stars were called hypergiants. Note that R136a1 is significantly smaller than stars that, it would seem, should be lower in class - for example, the supergiant UY Scuti. This is because it is not the largest stars that are called hypergiants, but the most massive ones. For such stars, a separate class was created on the spectrum-luminosity diagram (O), located above the class of supergiants (Ia). The exact initial mass of a hypergiant has not been established, but, as a rule, their mass exceeds 100 solar masses. None of the Big Ten's biggest stars live up to those limits.

Theoretical dead end

Modern science cannot explain the nature of the existence of stars whose mass exceeds 150 solar masses. This raises the question of how one can determine the theoretical limit on the size of stars if the radius of a star, unlike mass, is itself a vague concept.

Let us take into account the fact that it is not known exactly what the stars of the first generation were like, and what they will be like during the further evolution of the Universe. Changes in the composition and metallicity of stars can lead to radical changes in their structure. Astrophysicists have yet to comprehend the surprises that further observations and theoretical research will present to them. It is quite possible that UY Scuti 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.