The size of the stars is something that amazes us a lot. UY Scuti is a star 1700 times larger than the Sun, Stephenson 2-18. We are amazed and amazed to hear that the star is 2150 times the size of the Sun. (Size here means diameter)
However, there is an inaccuracy in comparing the sizes of the stars in this way. Such comparisons can give us a misconception about the size and weight of the stars. The Stephenson 2-18 star, which is said to be 2150 times larger than the Sun, is only 12 to 16 times heavier than the Sun.
During the lifetime of a star, there is a condition in which that star becomes too large. This condition is called Red Giant or Red super Giant. A star in this state would have grown to more than 200 times its actual size. Our sun itself will become a Red Giant in the future. Then the sun will be 200 times larger than it is now.
The aforementioned UY Scuti and Stephenson 2-18 are all now in their Red Super Giant status. That’s why they are so big. These are said to be 1700 times larger and 2150 times larger than the current size of the Sun. If we compare them to the size of the Sun when it became the Red Giant, the UY Scuti would be 8.5 times larger than the Sun. Just like Stephenson 2-18. 10.75 times the Sun.
What we really need to wonder about is stars that are many times heavier than the Sun. But none of our ordinary scientific media is so responsive to such stars.
None of us have ever heard of BAT99-98. It is a star 225 times heavier than the Sun. But it is only 37 times the size of the Sun. The rate at which the fusion reaction takes place within that one star is staggering. The surface temperature of that star is 45000 degrees Kelvin. The surface temperature of the Sun is only 5000 degrees Kelvin. Because the star has such a high temperature, most of the light emitted from it is ultraviolet light.