We see many stars in the night sky every day. As you know, our sun is also a star. Stars are very heavy objects in space due to which their gravity is very high. Stars tries to shrink due to the high gravity of the stars, but the fuel keeps burning inside the star and the nuclear reaction continues. Because of which a lot of energy comes out from inside it in the form of light and heat and we are able to feel that light and heat on the earth. Due to the nuclear reaction occurring within the star, the pressure inside the star starts to increase. The force generated by internal pressure fights with the gravity of the star. As long as the force inside the star keeps fighting with gravity, the star remains in balance. But as soon as the star’s fuel is gone, the nuclear reaction stops. Because of which the internal pressure on the star also ends and in the end, gravity wins.
The stars with similar size of our sun continue to glow for about 10 billion years. Our sun is four and a half billion years old and yet half of its fuel is over. When the star’s fuel starts to dissipate, the effect of gravity on it starts to increase. And there comes a time when there is no fuel left in the stars then the star shrinks and merges itself in its core (Gravity collapse the star). When the star shrinks, its shrinking speed is very fast, about one-fourth of the speed of light and in less than half a second a big star shrinks and turns into a small dense object. Because of this sudden collapse, Shock waves arise and the upper layer of the star explodes. After which a very large amount of energy and matter goes into outer space. When the star collapses, its brightness increases millions of times. But the occurrence of all these events depends on the size of the star.
If there is a sun-sized star, its brightness can continue for a few months until it reaches its peak. After that, the brightness of the star decreases and the star starts to cool down and after a few years, the temperature of the whole becomes equal to the temperature of space.
But if the star is 8 to 10 times the size of our Sun, then its fuel burns very fast. Due to the rapid burning of fuel, the life of the star is reduced. So a very strange phenomenon occurs when a big star collapses. That star turns into a neutron star. The mass of a neutron star is about 3 times that of our sun and it is very dense. Their gravity is also very high. The neutron star rotates at great speed on its axis. Because of their fast rotation, they become a strong magnetic field. From neutron stars, radiation is continuously emitted and it is seen blinking from the earth. These stars are also called pulsar stars. Gradually, after several millions of years, the energy of these pulsar starts start running out and then it becomes a normal neutron star.
But the stars whose size is 40 times more than our sun then their supernova explosion gives birth to a mysterious thing – Black hole.
When a very large amount of energy and matter goes into outer space then a black disc remains at the site of the explosion. This black disk is the most heaviest object in the universe. Its gravity is so high that even space time gets bend around it.
If you want to know about the black holes, then you can read these articles.
BIRTH OF A STAR
LIFE CYCLE AND DEATH OF A STAR
AMAZING FACTS ABOUT BLACK HOLE
The tenth brightest star in the night sky is named Betelgeuse and the second brightest star after rigel in the Orion constellation.
The Apparent Magnitude of betelgeuse is 0.4 . Keep in mind that the lower the apparent value of an astronomical object, the more it shines from the earth. The Apparent value of our sun is -26.7 and this is the most brightest star seen from the earth. The Apparent value of our moon is -12.6.
Betelgeuse’s mass is equal to 11 solar mass.
But when this star will have a supernova explosion then it can be seen very easily from the earth. Some astronomers say that when Betelgeuse explode, it will look brighter than our moon at night. And you can easily see this