6) A black hole is a part of space that has such a strong gravitational pull that nothing can escape from inside the black hole.
7) A Quasar is a very large celestial object that gives off massive amounts of energy. There is a theory that Quasars contain gigantic black holes in them but it is still yet to be proven.
8) The energy of a Quasar ranges from 1 trillion to 25 trillion of our sun.
9) Stars get their light due to a nuclear reaction that happens inside the star.
Therefore, in Doppler Effect only the frequency and wavelength are changes and the wave speed does not change