The night sky is dotted with billions of stars, and although they appear to be very small bright dots, they are truly huge and staggering in their size. Each such “firefly” in the sky is a huge plasma ball, in the depths of which powerful thermonuclear reactions occur, heating the stellar matter to thousands of degrees on the surface and up to millions of degrees in the center. From a great distance, the stars seem insignificant, but very beautiful and shining.
Comparative characteristics of stars
At present, only in our galaxy, astronomers count up to 400 billion stars, and in fact there are (in the part of the Cosmos accessible for study) about 170 billion galaxies in total! This number is almost impossible to imagine. In order to somehow navigate in this set, astronomers classify stars by luminosity, mass, size, type. InThe universe can meet such different stars as a red giant, a blue giant, a yellow dwarf, a 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 being discovered, and scientists have not yet learned how to accurately determine their size.
The word "star" also 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 heavenly bodies, they do not even dream of outshine the Sun with their own brilliance. But astronomers know that by the standards of the Universe, it is just a yellow dwarf. There are much larger celestial giants. Yes, yes, for the most impatient, we will immediately say that, unfortunately, the Sun is not the largest star. But which one is the largest?
The name of the largest star is UY from the constellation Scutum.
Difficulties in determining the size
There are two main difficulties in determining the comparative size. The first is the vast distances that exist in outer space. The remoteness does not allow to accurately determine the size of the star even with the most modern instruments, and as telescopes improve, the data is being refined all the time.
The second main difficulty is that stars are dynamic astronomical objects;many different processes. And part of the stars at the same time pulsates, changing its luminosity and magnitude. More recently, the celestial bodies, which bore 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 "in the sky" only at this particular moment in time. That is why the category of the largest stars will always be very relative and fickle.
Different sizes
All stars in the universe are very different sizes; they differ from each other, sometimes very strongly, by tens, hundreds or more times. The sun is far from the largest star, but you can’t call it the smallest either. Its diameter is 1.391 million kilometers. And at the same time, according to the stellar classification, it is the most typical “yellow dwarf”! Although this magnitude seems huge, there are stars that are several times larger. The largest (known to science) are Sirius, Pollux, Arcturus, Aldebaran, Rigel, Antares, Betelgeuse, Mu Cephei and VY constellation Canis Major. The latter, until recently, was the leader among all known stars.
Third number
The third largest star in the observable universe is WOH G64. This star is also classified as a red giant. It belongs to the constellation Golden Fish of the Large Magellanic Cloud. The light of this star flies to us for 163 thousand years. It is possible that the star exploded long ago, becoming a supernova, but we will not know about it until many thousands of years later.
The diameter of the record-breaking star is 1730 times greater than the diameter of our star.
Recent leader
For a long time, VY constellation Canis Major was considered the largest star. Its radius exceeds the solar one by about 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 the spacecraft 1200 years 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 on the other hand, the brightness of this star is incomparable with any celestial body observed from the Earth. It exceeds the solar 500 thousand times.
VY Canis Majoris was first observed by scientist Joseph Jérôme de Lalande, who recorded it in his star catalog. The date of this remarkable event is March 7, 1801. This VY has been pointed out to be of magnitude seven. 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 located close to each other, and is mistaken for one large star. It is now known that "discrete components" are in factare bright areas of the nebula that is located around the star. And this star is currently the second largest.
Interesting facts about VY Canis Major
With impressive brightness, the density of the star is quite 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 refer this supergiant to the category of unstable "old" stars and predict its explosion and transformation into a supernova within the next hundred thousand years. Luckily for us, VY from the constellation Canis Major is so far away from us that even when it explodes in a hundred thousand years, it will not harm the solar system in the slightest.
The star has been regularly observed since the 50s of the XIX century. During this time, the star has 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, pundits have managed to discover an even more impressive one. And in our own Milky Way galaxy.
According to the star catalogs, it passes as UY from the constellation of the Shield. This abbreviation denotes changes in the brightness of the glow, so the star belongs to the class of variables with an estimated pulsation 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 emission spectrum of these two stars, then 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 received the palm among the huge flaming beauties.
UY Shield Dimensions
The star UY Scutum is nine and a half thousand light years away from the solar system, so its dimensions can only be determined approximately. Its diameter is from 1.056 to 1.323 billion kilometers, which exceeds the diameter of our star by 1500-1900 times. But at the peak of the pulsation (and, as we remember, UY from the constellation of the Shield belongs to the category of changeable stars), the diameter can reach 2000 solar diameters! This makes it the largest star in the Milky Way galaxy and in the entire known universe.
For clarity: if you mentally place UY from the constellation of the Shield in the place of our native Sun, then it will not only absorb the nearest planets, including the Earth, but even "get" to Jupiter, and taking into account the highest of the radius estimates, it will also swallow the orbit of Saturn.
Another interesting figure that will help estimate the full degree of the hugeness of this largest star in the Universe: five billion yellow dwarfs like our Sun can fit in its volume.
So, we can conclude thatthe largest star known to science is UY from the constellation of the Shield, and this was described in detail in this article.
