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 that if such a star were placed in the place of the Sun, the current orbits of a terrestrial planet would be 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 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 the 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 star known today (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 current 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. The final stages of its evolution will be a supernova explosion, during which the star will shed its shell, most likely leaving behind a neutron star.
Already now, UY Scuti is showing its activity in the form of semi-regular variability with an approximate pulsation period of 740 days. Considering that the star can change its radius from 1700 to 2000 solar radii, the speed of its expansion and contraction is comparable to the speed of 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 us add to this the imperfection of modern methods for determining the distance to stars and a number of unspecified problems. It turns out that even among 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 largest star is practically impossible to find, 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, 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 measure 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.
Nothing can be true, but it's not true. There are much larger and more massive planets. For the entire Universe, our Earth is just a grain of sand lost in it. The solar system is only one of the elements of the Galaxy. The Sun is the main component of the Galaxy. Eight planets revolve around the Sun. And only the ninth - Pluto - was removed from the list of rotating planets because of its mass. Each planet has its own parameters, density, temperature. There are those that consist of gas, there are giant ones, small ones, cold ones, hot ones, and dwarf ones.
So what is the largest planet known so far? In the spring of 2006, an event occurred that shook the theory of celestial bodies. At the Lovell Observatory (USA, Arizona) in the constellation Hercules, a huge planet was discovered, twenty times the size of our Earth. Of the existing ones discovered today, this is the largest planet in the Universe. It is hot and similar to the Sun, but it is still a planet. It was called TrES-4. Its dimensions exceed the dimensions of the largest planet in the solar system - Jupiter - by 1.7 times. It is a giant gaseous ball. TrES-4 consists mainly of hydrogen. The largest planet orbits a star located at a distance of 1400. The temperature on its surface is more than 1260 degrees.
There are a sufficient number of giant planets, but so far no larger than TrES-4b has been discovered. The largest planet is more than 70% larger than Jupiter. The huge gas giant could be called a star, but its rotation around its star GSC02620-00648 definitely classifies it as planetary. As the responsible employee of the observatory G. Mandushev reported, the planet is more gaseous than solid, and you can only dive into it. Its density ranges from 0.2 g per cubic centimeter, which is comparable only to balsa (cork) wood. Astronomers are at a loss as to how this largest planet with such a low density has the ability to exist. Planet TrES-4 is also called TrES-4b. It owes its discovery to amateur astronomers who discovered TrES-4 thanks to a network of small automated telescopes located in the Canary Islands and
If you observe this planet from the ground, you can clearly see that it is moving along the disk of its star. The exoplanet orbits the star in just 3.55 days. Planet TrES-4 is heavier than the Sun and has a higher temperature.
The discoverers were Lowell employees, and later astronomers from the W.M. Hawaiian Observatory. Keck confirmed this discovery. Scientists at the Lovell Observatory have an assumption that the largest planet TrES-4 is not the only one in this constellation, and that it is quite possible that there may be another planet in the Hercules constellation. Lowell employees discovered Pluto in the solar system in 1930. However, in 2006, Pluto, in comparison with the giant TrES-4, began to be called a dwarf planet.
When people say “the largest planet,” Jupiter immediately comes to mind. Yes, this giant is more than 11 times larger in diameter than the Earth, and 317 times heavier. The Earth, compared to this planet, is just a dwarf, suitable only as a satellite. Of course, he is the king in our solar system, only the Sun is bigger than him. However, everything in the world is relative.
Therefore, Jupiter is not at all the largest planet known to science. After all, thousands of planets have now been discovered around other stars, and among them there are some very strange and remarkable ones. Each such planet is a world unlike the others, and a separate article can be written about each of them.
Until recently, the record holder for size was the planet Tres-4b, located in the constellation Hercules. From 2006 to 2011, it was the largest planet in the Universe. It is 1.706 times larger than Jupiter, almost twice. What is curious is that this planet is located in a binary system, and no other similar ones are yet known, because in such systems the gravitational forces of two stars act, preventing the formation of planets and stable orbits.
Planet Tres-4b is a gas giant similar to Jupiter and is located very close to its star - only 4.5 million kilometers. For comparison, the distance from the Sun to Mercury, the hottest planet in our system, is 58 million kilometers, and to Earth – 150 million!
Tres-4b completes a full orbit in just 3.5 days, and this ball of gas is very hot - its temperature exceeds 1700 degrees. Hot gas tends to expand, so this planet is “loose”, its density is very low, on average, like that of foam plastic or balsa wood. This is very little.
Although Tres-4b is a large planet, its mass is slightly less than that of Jupiter, and therefore its gravity is less. This hot gas planet, with its large size and low gravity, is not able to retain its substance, so it constantly loses it from its atmosphere. This gas plume trails behind the planet like a comet's tail.
This planet is a mystery to scientists. With such a gigantic size and disproportionately small mass, it simply should not exist. Yes, now it is losing mass, but how could it even form under such conditions? Maybe it was once not so hot, and therefore was smaller and more dense, like Jupiter? Then in the past it was much further from the star or was completely captured by the star somewhere along the way.
Unfortunately, it is not possible to look at this planet live in the foreseeable future - the distance to it is unimaginably large, 1600 light years.
This huge planet was discovered by the transit method back in 2006, and the results were published a year later.
The program within which the research was carried out is called TrES - Trans-Atlantic Exoplanet Survey, or Trans-Atlantic Exoplanet Survey. It involves three small 10-centimeter telescopes from different observatories, equipped with Schmidt cameras and auto-search. A total of five exoplanets were discovered as part of this program, including Tres-4b.
The largest planet in the Universe - HAT-P-32b
In 2011, the new largest planet in the Universe was discovered, which turned out to be larger than Tres-4b. It is located in the constellation Andromeda, at a distance of 1044 light years from us.
This planet has a radius of 2.037 times Jupiter, making it slightly larger than Tres-4b. But its mass is approximately the same, and slightly less than Jupiter’s. Otherwise, HAT-P-32b is very similar to Tres-4b.
This planet is also a hot ball of gas, even hotter. Its temperature reaches 1888 degrees. This planet is also located close to the star - at a distance of about 5 million kilometers, and due to its enormous temperature, its gas also expands and is lost. Therefore, its density is also low.
Scientists are constantly discovering new planets around other stars, and it is possible that this record will be broken, and soon we will learn about the other largest planet in the Universe.
Our Universe is truly huge. Pulsars, planets, stars, black holes and hundreds of other objects of incomprehensible size that are found in the Universe.
And today we would like to talk about the 10 biggest things. In this list, we've put together a collection of some of the largest objects in space, including nebulae, pulsars, galaxies, planets, stars, and more.
Without further delay, here is a list of the ten biggest things in the universe.
The largest planet in the Universe is TrES-4. It was discovered in 2006 and is located in the constellation Hercules. The planet, called TrES-4, orbits a star that is about 1,400 light-years away from planet Earth.
The planet TrES-4 itself is a ball that consists primarily of hydrogen. Its dimensions are 20 times greater than the size of the Earth. Researchers claim that the diameter of the discovered planet is almost 2 times (more precisely 1.7) larger than the diameter of Jupiter (this is the largest planet in the solar system). The temperature of TrES-4 is about 1260 degrees Celsius.
By far the largest star is UY Scuti in the constellation Scutum, about 9,500 light-years away. This is one of the brightest stars - it is 340 thousand times brighter than our Sun. Its diameter is 2.4 billion km, which is 1700 times larger than our star, with a weight of only 30 times the mass of the sun. It’s a pity that it is constantly losing mass; it is also called the fastest burning star. This may be why some scientists consider NML Cygnus the largest star, and others consider VY Canis Majoris.
Black holes are not measured in kilometers; the key indicator is their mass. The largest black hole is in the galaxy NGC 1277, which is not the largest. However, the hole in the galaxy NGC 1277 has 17 billion solar masses, which is 17% of the total mass of the galaxy. By comparison, our Milky Way's black hole has a mass of 0.1% of the galaxy's total mass.
7. Largest galaxy
The mega-monster among the currently known galaxies is IC1101. The distance to Earth is about 1 billion light years. Its diameter is about 6 million light years and holds about 100 trillion. stars; for comparison, the diameter of the Milky Way is 100 thousand light years. Compared to the Milky Way, IC 1101 is more than 50 times larger and 2,000 times more massive.
Lyman-alpha blobs (drops, clouds) are amorphous bodies resembling amoebas or jellyfish in shape, consisting of a huge concentration of hydrogen. These blots are the initial and very short stage of the birth of a new galaxy. The largest of them, LAB-1, is more than 200 million light years wide and is located in the constellation Aquarius.
In the photo on the left, LAB-1 is recorded by instruments, on the right is an assumption of what it might look like up close.
A radio galaxy is a type of galaxy that has much greater radio emission compared to other galaxies.
Galaxies, as a rule, are located in clusters (clusters), which have a gravitational connection and expand with space and time. What is located in those places where there are no galaxies? Nothing! Regions of the Universe in which there is only “nothing” and is emptiness. The largest of them is the emptiness of Bootes. It is located in close proximity to the constellation Bootes and has a diameter of about 250 million light years. Distance to Earth approximately 1 billion light years
The largest supercluster of galaxies is the Shapley supercluster. Shapley is located in the constellation Centaurus and appears as a bright clump in the distribution of galaxies. This is the largest array of objects connected by gravity. Its length is 650 million light years.
The largest group of quasars (a quasar is a bright, energetic galaxy) is the Huge-LQG, also called U1.27. This structure consists of 73 quasars and has a diameter of 4 billion light years. However, the Great GRB Wall, which has a diameter of 10 billion light years, also claims primacy - the number of quasars is unknown. The presence of such large groups of quasars in the Universe contradicts Einstein’s Cosmological Principle, so their research is doubly interesting for scientists.
If astronomers have disputes about other objects in the Universe, then in this case almost all of them are unanimous in the opinion that the largest object in the Universe is the Cosmic Web. Endless clusters of galaxies surrounded by black matter form “nodes” and, with the help of gases, “threads”, which in appearance are very reminiscent of a three-dimensional web. Scientists believe that the cosmic web entangles the entire Universe and connects all objects in space.
