Formation of Heavenly Bodies in Universe.

 How is white dwarf formed ?

- If mass of Star is equal or less than Sun after nova explosion core of the star  contracts continuously which increases the core temp and glows with white light which is called white dwarf . Later it changes into black dwarf.

  How is neutron  star formed?
 If mass of the star is up to 5 times of the Sun after supernova explosion, core of the star contracts continuously unless the electron neutralizes with proton of nucleus Thus the mass consists only neutron and called neutron star It does not emit light but radiates radio frequency (Pulsar).

 Note: Our Sun later changes into white dwarf.

How is black hole formed? why it is invisible?   If mass of star is. more than 5 times of the sun, after supernova explosion, core of star contracts uncontrolled way and whole mass is concentrated of a point. It has infinite mass with infinite force of gravity from where even light can't escape away which is called black hole. As light can't reflect back from the mass, it is invisible and named as BLACK HOLE.