2) Eventually, the hydrogen in the centre of the star will run out. A star uses but a small portion of its matter as fuel, and when this fuel is exhausted, it dies off. The lifetime that ALLAH designed for the living had also been distributed for the stars.
3) Gravity will take over and the centre of the star will shrink. This is called gravitational collapse.
Gravitational collapse in astronomy is the inward fall of a massive body under the influence of the force of gravity. It occurs when all other forces fail to supply a sufficiently high pressure to counterbalance gravity and keep the massive body in hydrostatic equilibrium.
In this sense a star is in a "temporary" equilibrium state between a gravitational collapse at stellar birth and a further gravitational collapse at stellar death.
Let’s see how stars come to the Black holes.
(A star)
Gravitational Collapse
(a) The onion-layered shells of elements undergo fusion, forming an iron core (b) The star on hydrogen (c) Infalling material to bounce (d) The red lines are the star on gravity both the effects cancel out each other (e) The surrounding material is blasted away (f) Fuel of stars is run out and gravity takes place.
4) As the centre collapses, it becomes very hot again, eventually getting hot enough to start a new kind of nuclear fusion with Helium as the fuel.
5) Then they grow in size, as if magnified, and become Red giant or super giant.
6) Their temperature, around 15 million degrees, rises up to 100 million degrees.
(Red Giant)
(Super Giants)
7) The area covered by a super giant is so vast that it can easily contain more than sixty million suns. The immensity of these numerical values is indicative of the magnitudes indicated in 76th verse of the sura.
8) Then the Red Giant shrinks and the star looks “normal” again.
9) This does not last very long, though, as the Helium runs out very quickly and again the star forms a Red Giant
10) Eventually it can become almost as small as human being, but with the same mass as a whole star! This very dense object is called a White Dwarf.
11) Because the star was so big, the collapse does not stop even with a White Dwarf, but an even denser object called a Neutron Star (Pulsar) is made.
12) The outer parts of the star (that formed the Red Giant) then drift off into space and cool down making a Planetary Nebula.
Here you can see a planetary nebula with its White Dwarf in the middle:-
Planetary nebula M57
The Cat's Eye Nebula
The Helix Nebula
The Ring Nebula
The Eskimo Nebula
The Dumbbell Nebula
13) For more massive (bigger) stars than the Sun, many more types of nuclear fusion can take place. This means several more Red Giant stages. However, eventually even the biggest stars run out of fuel and finally collapse
14)For the biggest stars, this collapse causes a huge explosion called a Supernova! A Supernova can be brighter than an entire galaxy of 100,000,000,000 stars!
Tyco and Cas A
The Crab Nebula is a pulsar wind nebula Tycho and Cas Aassociated with the 1054 supernova
15) Stars supposed to form in the final stage of the stellar evolution; these consist of a super dense mass mainly of neutrons having a strong attractive force. The matter in the neutron stars is extremely dense. Just to give you an idea, a teaspoonful of this matter would weigh one billion tons. The density of a Neutron star is about 1x1018 kg/m3 (that is 1,000,000,000,000,000,000!)
16) The end states are called compact stars (Very massive and have a small radius but actual structure is not known). In astronomy the term compact star (sometimes compact object) is used to refer collectively to white dwarfs, neutron stars, other exotic dense stars, and black holes.
21) Sometimes the collapse cannot stop at all and a Black Hole is made, from which not even light can escape.
BLACK HOLE
Black Hole in front of the Milky Way. The hole has 10 solar masses and is viewed from a distance of 600 km. An acceleration of about 400 million g is necessary to sustain this distance constantly.
