The night sky is dotted with billions of stars, and although they seem very small bright points, in fact they are truly enormous and amazing in their imagination. Each such “firefly” in the sky is a huge plasma ball, in the depths of which powerful thermonuclear reactions occur, warming stellar matter to thousands of degrees on the surface and to millions in the center. From a great distance, the stars seem insignificant, but very beautiful and shining.
Comparative characteristics of stars
Currently, only in our galaxy, astronomer scientists count up to 400 billion stars, and in fact there are (in the accessible to study part of the Cosmos) about 170 billion galaxies! This number is almost impossible to imagine. In order to somehow orient themselves in this set, astronomers classify stars according to luminosity, mass, size, type. In the Universe, one can meet such different stars as the red giant, the blue giant, the yellow dwarf, the neutron star, and so on. The largest of the stars are often called hypergiants. Those that are smaller are called supergiants. And sometimes it’s quite difficult to understand which star is the largest. After all, new stars and galaxies are constantly opening up, and scientists have not yet learned how to determine their size with accuracy.
The word "star" has a figurative meaning. But those who are accustomed to shine on Earth (musicians, the biggest porn stars, Hollywood celebrities, outstanding artists and models) cannot even dream of competing in greatness with the heavenly bodies, they do not even dream of overshadowing the Sun with their own brilliance. But astronomers know: by the standards of the universe, it is just a yellow dwarf. There are much larger celestial giants. Yes, yes, for the most impatient, let's say right away that, unfortunately, not the Sun is the biggest star. But which is the largest?
The name of the largest star is UY from the constellation Shield.
Difficulties in sizing
There are two main difficulties in determining the comparative size. The first is the vast distances existing in outer space. The remoteness does not allow to accurately determine the size of a star even by the most modern instruments, and as telescopes improve, the data is constantly updated.
The second main difficulty is that stars are dynamic astronomical objects, a lot of various processes occur in them. And part of the stars pulsates, changing its luminosity and magnitude. More recently, celestial bodies, bearing the title of the largest stars, said goodbye to him for this reason. Especially “suffer” from this red giants, which belong to the category of the most huge. For this reason, the classification of stars by magnitude in any case will reflect the state of "in the sky" only at a given particular moment in time. That is why the category of the largest stars will always be very relative and unstable.
Different sizes
All stars in the universe have very different sizes; they differ from each other, sometimes, very much, tens, hundreds and more times. The sun is by no means the largest star, but you cannot name it the smallest either. Its diameter is 1.391 million kilometers. And at the same time, according to stellar classification, she is a typical "yellow dwarf"! Although this value seems huge, there are stars and several times more. The largest (known to science) are Sirius, Pollux, Arcturus, Aldebaran, Rigel, Antares, Betelgeuse, Mu Cepheus and the VY constellation Canis Major. The latter, until recently, was the leader among all the famous stars.
Third number
The third largest star observed by the universe is WOH G64. This star is also categorized as red giants. It belongs to the constellation Golden Fish of the Great Magellanic Cloud. The light of this star flies to us 163 thousand years. Perhaps the star exploded for a long time, becoming a supernova, but we will only know about it after many thousands of years.
The diameter of the record star exceeds the diameter of our luminary by 1730 times.
Recent leader
For a long time, the VY constellation of the Great Dog was considered the largest star . Its radius exceeds Solar by approximately 1300 times. Its diameter is 2 billion kilometers. This star is located 5 thousand light-years from our native solar system. One revolution around VY would take 1200 years for a spacecraft if its speed was 800 kilometers per hour. If we reduce the diameter of the Earth to 1 centimeter and compare it, thus, with VY, then the diameter of the star would be 2.2 kilometers by such standards. Although the mass of the star is not so impressive - it is only 40 times heavier than the sun. But the brightness of this star is incomparable with any celestial body observed from the Earth. It exceeds the sun by 500 thousand times.
For the first time, the VY of the Great Dog was observed by the scientist Joseph Jerome de Lalande, he recorded it in his star catalog. The date of this remarkable event is March 7, 1801. It was indicated that this VY has a seventh magnitude. After 46 years, observations were made, as a result of which it turned out that the star has a crimson color. Then it was discovered that this star has 6 discrete components, so it is most likely a multiple star. A multiple star is one that consists of several stars close to each other, and is mistakenly taken as one large star. Currently, it is already known that the "discrete components" are actually bright areas of the nebula that is located around the star. And this star currently ranks second in size.
Interesting facts about VY Big Dog
With impressive brightness, the star’s density is very low. It is only five times the density of ordinary water. For comparison, the density of the Sun's matter is 1.409 of the density of water.
Astronomers attribute this supergiant to the category of unstable "old" stars and predict its explosion and transformation into a supernova in the next hundred thousand years. Fortunately for us, VY from the constellation Canis Major is so far away from us that even when it explodes after a hundred thousand years, not a bit will harm the solar system.
The star has been regularly observed since the 50s of the XIX century. During this time, the star lost a significant part of its luminosity. Scientists believe that this process is associated with the loss of stellar matter, the star simply “burns out”.
Leader today
No matter how huge the previous star was, pundits managed to discover even more impressive. And in our own galaxy, the Milky Way.
According to star catalogs, it passes as UY from the constellation Shield. This abbreviation refers to changes in the brightness of the glow, so the star belongs to the class of variables with an approximate ripple period of 740 days. If we compare the luminosity of the leader star with the luminosity of our Sun in the spectrum visible to the naked eye, then it is more than 120 thousand times. If we take into account the infrared radiation spectrum of these two stars, we get an even more impressive figure - 340 thousand times!
Although it was first discovered by German astronomers in Bonn back in 1860, it was possible to determine its true size only in 2012, using the American telescope located in the Atacama Desert. Then she got the palm among the huge flaming beauties.
Dimensions UY Shield
The UY Shield star is nine and a half thousand light-years distant from the Solar System, so you can only determine its size approximately. Its diameter is from 1,056 to 1,323 billion kilometers, which exceeds the diameter of our star by 1,500-1,900 times. But at the peak of the pulsation (and, as we recall, UY from the constellation Shield belongs to the category of changeable stars), the diameter can reach 2000 solar diameters! This makes her the largest star in the Milky Way galaxy and in the entire explored Universe.
For clarity, if you mentally place the UY from the constellation Shield into the place of our native Sun, then it will not only absorb the nearest planets, including the Earth, but even “reach” Jupiter, and taking into account the highest radius estimate, it will also absorb Saturn’s orbit.
Another interesting figure that will help evaluate the full extent of the enormity of this largest star in the Universe: in its volume, you can place five billion yellow dwarfs, like our Sun.
So, we can conclude that the largest star known to science is UY from the constellation Shield, and this was described in detail in this article.