The most famous stars in space. The largest star in the milky way galaxy
Stars are huge balls of burning plasma. But, with the exception of the Sun, they appear as tiny points of light in the night sky. Moreover, our Sun is not the smallest or largest star. There are many much more massive and larger stars than the Sun. Some of them have evolved since their formation. Others grow as they “age.”
To answer the question about which star is the largest in the universe, we “sorted” the stars according to such criteria as size. The equatorial radius of the Sun, which is 696,392 kilometers, was taken as a unit of measurement for the stellar radius.
This celestial body, also known by another name (HR 5171 A), belongs to the yellow hypergiants and is a double star. Its smaller “partner” HR 5171 B orbits V766 Centauri every 1,300 Earth days.
This star is located in the direction of the constellation Cepheus, about 5 thousand light years from Earth. The red hypergiant, with a radius approximately equal to 1050-1900 solar radii, is part of a binary star system. Its companion is the small blue star VV Cephei B, which orbits its “big brother” in an elliptical orbit. The star is named after the larger of the pair, and is now known as one of the largest double stars in the Milky Way.
To get a closer look at this red supergiant from the constellation Scorpio, people would have to travel a distance of 7,400 light-years. The radius of Scorpio AH is 1411 times greater than the solar radius.
7. VY Canis Majoris
This star is associated with heated debate among astronomers. According to estimates updated in 2012, its radius exceeds the radius of the Sun by 1420 times. However, according to Robert Humphreys' initial estimate, the radius of VY Canis Majoris is 1800 to 2200 times that of the Sun. The exact radius of the stellar giant has not yet been established. When it can be known for sure, the leader in the ranking of the biggest stars may change.
The radius of this hypergiant star is at least 1,420 times the radius of the Sun, and its brightness level is as much as 300,000 times higher than the Sun. It is located in the constellation Cygnus, at a distance of about 5 thousand light years from Earth.
This star belongs to the class of hypergiants - the most powerful and brightest, the heaviest and at the same time the rarest and short-lived supergiants. Its radius is approximately 1520 times greater than the solar radius.
VX Sagittarius is located in the constellation Cepheus, 9000 light years from our planet. It is so huge that it could easily cover the orbital path of Saturn if it were in the place of the Sun. The star's red color indicates that its temperature range is between 3000 and 4000 Kelvin. Hotter stars have a yellow color, while very hot ones take on a bluish tint.
At a distance of 11,500 light years from our planet, in the star cluster Westerland 1, lies the fourth largest star in the galaxy. Its luminosity is 380 thousand times greater than the Sun, and if placed in the place of our yellow star, its photosphere would absorb the orbit of Jupiter. The photosphere is where the star becomes transparent to light, and where photons—that is, light particles—can disappear. The photosphere allows astronomers to approximate the “edges” of a star.
Here is another star known to science from the constellation Cepheus, included in the list of the largest. The radius of this red supergiant is about 1600 solar radii. If RW Cephei were in the place of the Sun, the radiating layer of its stellar atmosphere (photosphere) would extend beyond the orbit of Jupiter.
The second largest star in space is located in the constellation Doradus, 160 thousand light years from our world. Despite the fact that this star has lost up to a third of its original mass due to stellar wind, a thick ring layer of gas and dust torus has formed around it for many years. The star's "dimensions" were adjusted to take into account all the mass present in its ring. It is expected to go supernova in a couple of thousand years.
1. UY Scuti (UY Scuti) - the largest star in the universe
At a distance of 9,500 light years from the Sun, in the constellation Scutum, lies the largest star in the world. Its estimated size is almost eight astronomical units, where one astronomical unit is the distance between the Earth and the Sun. This is enough to extend the UY Scuti photosphere into Jupiter's orbit.
UY Scuti is so gigantic and so bright that you can see it with powerful binoculars on a dark night. It is visible along the stars of the Milky Way, and appears as a reddish star with a faint spot.
Study of a supergiant
In the summer of 2012, astronomers, using the Very Large Telescope complex located in the Atacama Desert in Chile, measured the parameters of three red supergiants near the Galactic center. The objects of study were UY Scutum, AH Scorpio and KW Sagittarius.
Scientists have determined that all three stars are 1,000 times larger and more than 100,000 times brighter than the Sun. They also made the discovery that UY Scuti is the largest, brightest of all three stars. From the radius and luminosity, an effective temperature was obtained - 3665 ± 134 K.
Mass and dimensions of UY Scuti compared to the Sun
The exact mass of this star is unknown, primarily because it has no visible companion star from which its mass can be measured by studying gravitational interference. According to stellar evolutionary models, the star's initial mass (at formation), corresponding to a red supergiant stage such as UY Scuti, would have been around 25M☉ (possibly up to 40M☉ for a non-rotating star) and would have burned continuously. Presumably, its current mass is 7-10 M☉ and continues to decrease. UY Scuti is not only the largest, but also the fastest burning star currently known to science.
UY Scuti's mass is just over 30 times the mass of our Sun, which doesn't even approach the top of the list of most massive stars. This honor belongs to the star R136a1, which has 265 times the mass of the Sun, but only 30 times the radius of the Sun.
Mass and physical sizes do not always correlate for celestial bodies, especially for giant stars. Thus, although UY Scuti is only 30 times more massive than the Sun, it has a radius somewhere in the region of 1,700 times the radius of our daylight star. The error in this measurement is about 192 solar radii.
Is life possible near UY Scuti
The habitable zone, or the orbital zone with the highest probability of life, is a complex thing, the possibility of which depends on several factors. The planet on which life originated should not be too far or too close to the star. According to astronomers, the habitable zone around UY Scuti will be from 700 to 1300 astronomical units (AU). This is an insanely long distance. The number in kilometers is simply incomprehensible - it is about 149,597,870,700 km. For comparison, the habitable zone in the Solar System is located at a distance of 0.95 to 1.37 AU from the Sun.
If a living planet is at a safe distance of, say, 923 astronomical units from UY Scuti, its year will last 9612 Earth years. That's almost 2500 years of winter! And 2500 years of summer. That is, many generations will change who know only one season.
UY Scuti may indeed have a planetary system in this zone, but if it does, it won't last very long. You, the reader, may reasonably ask: “Why”? Because the star's future is too bright.
What awaits the star in the future?
Based on current models of stellar evolution, scientists speculate that UY Scuti began to fuse helium into a shell around its core. As the helium flows out, the star will begin to drain heavier elements such as lithium, carbon, oxygen, neon and silicon. The star's location deep in the Milky Way suggests that it is rich in metal. After the fusion of heavy elements, its core will begin to produce iron, upsetting the balance of gravity and radiation, resulting in a supernova. This will happen in a million years - not very long by astronomical standards, but humanity has time to prepare for such an enchanting spectacle.
After the supernova, UY Scuti will most likely become a yellow hypergiant, a blue variable star, or even a Wolf-Rayet star with very high temperature and luminosity. In the latter case, it will “give birth” to many new stars after its supernova.
Modern astronomy defines stars as huge plasma balls consisting of incandescent mass. Humanity has always been interested in the question of what is the largest star in the Universe and what is its size. This rating includes the TOP 10 largest such objects known to mankind. However, it has a certain degree of convention - there are probably even larger luminaries in space, but we don’t know about them yet, and some of them are variable stars capable of contracting and expanding.
Mu Cephei
One of the largest and most powerful stars in our Galaxy with a luminosity 350 thousand times greater than the Sun is rightfully included in the TOP ten stars of our rating. It is approximately 650-1420 times larger than our star, and from its size it becomes clear which largest star is huge. Mu Cephei can accommodate up to 1 billion Suns and 2.7 quadrillion objects such as Earth in its area. If we imagine our planet in the form of an ordinary golf ball with a diameter of 4.3 cm, the width of this star on this scale would be 5500 meters, which is twice the corresponding size of the Golden Gate Bridge. Mu Cephei is 60 thousand brighter than the Sun, and its bolometric luminosity exceeds the solar luminosity by 350 times. At the same time, it belongs to the category of dying, since scientists have recorded irreversible processes of carbon synthesis on it.
V766 Centauri
The ranking of the largest stars also includes yellow supergiants. The radius of V766 Centauri is 1490 times larger than the Sun. The object has one distinctive feature - in fact, it is a double star together with HR 5171. Its “companion” is much smaller and is so close that it practically touches the more massive star. They are located in the constellation of the same name at a distance of about 12 thousand light years from the Sun.
AN Scorpio
Being a red supergiant with a radius of approximately 1411 solar, the object confirms the assumption of what the largest star looks like and what size it is. It is separated from Earth by 7.4 thousand light years. The star is surrounded by a dusty shell, and sources of its microwave radiation include water and silicon oxide. During the observation period, they approached AN Scorpius at a speed of 13 km/s, which confirmed the ongoing process of compression of the giant.
KY Swan
The hypergiant, thanks to its radius of 1420 solar, rightfully took its place in the TOP 10 largest stars in the Universe. This is a borderline star, and if it had a lower luminosity, it would no longer be classified as a supergiant. Located 5 thousand light years from Earth. KY Cygni is a very bright object that exceeds our star in this indicator by at least 138 thousand times.
VX Sagittarius
Another red supergiant included in the list of the largest. It belongs to the group of semi-regular variable stars; according to scientists, it is gradually losing mass due to the influence of stellar wind. Large stars in the Universe, as a rule, are located at a great distance from Earth, and VX Sagittarius is no exception - it is separated from our planet by about 5250 light years. The radius of the giant star ranges from 850 to 1940 solar, and its diameter probably exceeds the similar parameters of the asteroid belt of the Solar System.
Westerland 1-26
A red hypergiant located in the constellation Altar. It was discovered by the Swedish astronomer B. Westerlund in the star cluster system Westerlund 1. Anyone who wonders what the largest star is called needs to know that the luminosity of Westerlund 1-26 exceeds that of the Sun by 380 thousand times, and its surface temperature exceeds 3000 K. In the ESO photograph Westerlund 1 appears to be one of the most massive open clusters in the Galaxy.
RW Cepheus
A red hypergiant whose name comes from the constellation Cepheus. It is located 11.5 thousand light years away from our planet. It is no coincidence that it is included in the TOP 10 largest stars, since its radius is 1535 times greater than the solar radius. The luminosity of this large object is 625 thousand times greater than that of the Sun. At the end of its life, it can become a hypernova, and its core transforms into a black hole.
WON G64
The red supergiant of the Doradus constellation, the second largest star in the Universe. Its estimated radius can reach at least 1540 solar. According to astrophysicists, this large object, one of the TOP largest stars, has lost up to 1/3 of its mass due to stellar wind. Using the Very Large Telescope complex located in Chile, it was possible to obtain an image that helps to understand that the dust and gas around WON G64 forms a torus, reducing its luminosity to 280 thousand solar.
VY Canis Majoris
The hypergiant, well known to astronomers, which is named after the constellation of the same name, reaches a size of 1600 solar radii. Moreover, the mass of the object included in the list of the largest stars is only 17 times greater than the Sun, which confirms its extremely low density. The volume of the giant is 7·10 15 times greater than that of the Earth. Astrophysicists studying the star using the Hubble Space Telescope say it will explode as a hypernova in 100,000 years. This photo of VY Canis Majoris shows the star expelling large volumes of gas during its outburst.
UY Shield
A true supergiant located in the Scutum constellation. According to astronomers, its radius is 1708 solar, and its diameter reaches 2.4 billion km. The largest star in the Galaxy has a volume that exceeds the parameters of the Sun by 5 billion times. The star is defined as a variable red hypergiant with an estimated pulsation period of 740 days. In the visible part of the spectrum, its luminosity exceeds that of the sun by 120 thousand times; in the absence of accumulations of cosmic dust, UY Scuti could be one of the five objects that can be viewed from Earth with the naked eye.
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 been able to discover and register approximately 50 billion stars. More advanced technology makes it possible to explore remote corners of space and obtain 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, when observing a star, it is quite difficult to estimate the distance to it. Therefore, before you set out on a quest to determine which is the largest star in our galaxy, it is necessary to understand the level of difficulty in observing space objects.
Previously, until the beginning of the twentieth century, it was believed that our galaxy was 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 a lot of galaxies, and ours is not the largest.
Space 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 a hundred or more million light years. During the research process, new objects are discovered. The discovered stars are compared and the most unique and largest are determined.
Supergiant in the constellation Scutum
The name of the largest star in our galaxy is UY Scuti, a red supergiant. This is a variable that varies from 1700 to 2000 solar diameters.
Our brain is not able to imagine such quantities. Therefore, to fully understand the size of the largest star in the galaxy, it is necessary to compare it with values that are understandable to us. Our solar system is suitable for comparison. The size of the star is so large that if it were placed in the place of our Sun, the boundary of the supergiant would 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 Scuti - can only conditionally be considered a “king”. The reasons are obvious. One of them is the vast distances in space 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 1,700 times larger than our celestial body, the largest star in our galaxy is only 7-10 times more massive. It turns out that the density of the supergiant is millions of times less than the air around us. Its density is comparable to 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 a 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 to our Sun at the end of evolution) and began actively burning helium and a number of other elements heavier than hydrogen. After a few million years, the largest star in the galaxy - UY Scuti - 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 supergiant UY Scuti - about ten stars with similar sizes can be noted. These include VY Canis Majoris, Cepheus A, NML Cygnus, WOH G64 VV and several others.
It is known that all the largest stars are short-lived and very unstable. Such stars can exist for millions of years or several thousand years, ending their life cycle in the form of a supernova or black hole.
The biggest star in the galaxy: the search continues
Observing the major changes over the past twenty years, it is worth assuming that over time our understanding of the possible parameters of supergiants will differ from previously known ones. 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 prompt scientists to revise previously accepted dogmas and definitions.
The star - VY Canis Majoris is the largest of all known stars in the Milky Way. Mention of it can be found in a star catalog published back in 1801. There she is listed as a seventh magnitude star.
The red hypergiant star VY Canis Majoris is located 4,900 light-years from Earth. It is 2100 times larger than the Sun. In other words, if we imagine that VY suddenly appeared in the place of our star, then it would absorb all the planets up to Saturn. In order to fly around such a “ball” at a speed of 900 km/h it will take 1100 years. However, when moving at the speed of light, it will take much less time - only 8 minutes.
Since the mid-19th century, VY Canis Majoris has been known to have a crimson hue. It was assumed that it is a multiple. But later it turned out that this is a single star and it does not have a companion. And the crimson spectrum of the glow is provided by the surrounding nebula.
3 or more stars that are seen as closely spaced are called a multiple star. If in fact they are simply close to the line of sight, then they are an optically multiple star; if they are united by gravity, they are a physically multiple star.
With such a gigantic size, the mass of the star is only 40 times the mass of the Sun. The density of the gases inside it is very low - this explains its impressive size and relatively low weight. 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 mid-19th century, scientists noted that the giant star was losing its brightness. However, this parameter is still very impressive - the brightness of VY is 500 times greater than the Sun.
Scientists believe that when VY's fuel runs out, it will explode as 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 had 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 research was carried out using the Hubble telescope.
The mass of the discovered star is close to the theoretically calculated lower limit and amounts to 8.3% of the mass of the Sun. The existence of smaller stellar objects is considered impossible. Their small size simply does not allow the nuclear fusion reaction to begin. The brightness of such objects is similar to the glow of a candle lit on the Moon.
