Chapter 27, Problem 1E

Describe some differences between quasars and normal galaxies.

To determine

The difference between quasars and normal galaxies.

Answer to Problem 1E

Quasar is an active galaxy or young galaxy while normal galaxy is the regular galaxy, which was once a quasar but materials falling into it runs out.

Explanation of Solution

Quasars are young galaxies having large amount of gas and dust around their centers. The constituents around centers form a disc called as accretion disc spiraling into the black holes.

Friction and gravitational effects heat the disc as more and more constituents falling into it and it emits the electromagnetic radiation having vast amount of energy.

Existence of quasar lasts until the constituents are falling into it. Once constituents run out, it remains no more quasars and converts into a normal galaxy.

Difference between quasars and normal galaxies:

• Quasars move with more speed than normal galaxies.
• Quasars are small in comparison to normal galaxies.
• Quasar’s emission lines shifts far to the red wavelength ranging from 15% to more than 96% the speed of light while a normal galaxy have both red and blue shifts.
• Quasars are 10 to 100 times more luminous than brighter normal galaxies.
• Quasar’s infrared and X-ray bands are brighter than normal galaxy.

Conclusion:

Thus, quasar is an active galaxy or young galaxy while normal galaxy is the regular galaxy, which was once a quasar but materials falling into it runs out.