What is the biggest star in the universe?

The size of certain stars present in the universe impresses compared to that, modest, of the Sun. The mass of other stars is also amazing (a big star is not necessarily very massive and vice versa). Here are the most remarkable cases known to astronomers.

There are so many stars in the universe that it is impossible to know them all. Besides, we don't even know how many there are in our galaxy. For astronomers, it is rather a question of assessing their mass by taking that of the Sun as a reference: 1.98892 x 1030 kg, or 333,000 times that of Earth or 1,048 times that of Jupiter. For example, the Milky Way has an estimated mass of about 240 billion times that of the Sun.

Of yellow dwarf type, the Sun is a star with relatively modest dimensions. Its diameter is 1.392 million km, or 109 times that of Earth. It would take about 1.3 million planets similar to ours to fill it completely. Finally, note that our star alone represents 99.86% of the total mass of the Solar System.

In terms of star, there are therefore two kinds of colossi: the giant and the massive.

VY Canis Majoris or UY Scuti: which is the biggest star?

Not so long ago, it was VY Canis Majoris who held the record. The size of this star, located in our Galaxy, some 5,000 light years from Earth, in the direction of the constellation of the Big Dog, has been revised downwards: between 1,420 and 1,540 times that of the Sun, all the same nearly 2 billion km in diameter, 13 times the distance between Earth and the Sun.

VY Canis Majoris has been dethroned by another red supergiant: UY Scuti (at 9,500 light years in the constellation of Sobieski's shield); 1,700 times larger than the Sun, it could extend to Saturn if we put it in the center of the Solar System!

Mu Cephei or Erakis, "the Garnet Star"

About 1,200 times larger than the Sun, Mu Cephei or Erakis - nicknamed "the Garnet Star" by William Herschel - is famous for being visible in this color and without instrument, within the constellation of Cepheus, some 5,200 light years.

In any case, their excessive size is synonymous with decline. Their color testifies to their cooling surface.

Eta Carinae and the stars of the R136 cluster, very massive stars

Although less large, the very massive stars impress with their ardor and their vigor. One of the most well-known extreme cases in our Galaxy is that of Eta Carinae, 7,500 light years from Earth; 120 times more massive than the Sun for 250 times its size, this star is a million times brighter than our star. It was undoubtedly even more massive in its youth, but as it got older, it did not stop losing weight: about 500 land masses per year. It is not far from exploding now, which promises an extraordinary celestial spectacle in the relatively near future.

Even more colossal are those which appear in the R136 cluster, within the Tarantula nebula in the dwarf galaxy of the Large Magellanic Cloud, about 170,000 light years from Earth. Nine of these young stars have a mass 100 times greater than that of the Sun. Together, they are 30 million times brighter than the latter! With 250 times the mass of the Sun, R136a1 is by far the most massive star known. Currently, it shines as much as 10 million suns! Astronomers wonder about the processes that could have generated such gigantism, because the theoretical limits are 150 solar masses.