Identify the general types of spectra produced by stars, emission nebulae, galaxies and quasars
- Due to cool atmosphere of stars, they produce absorption spectra.
- Emission nebulae are regions of hot gas that produce emission spectra.
- Emission nebulae also show a faint continuous spectrum produced by the reflection of starlight.
- Galaxies produce an almost complete spectrum.
- Most galaxies emit light characteristic of older stars.
- Some galaxies show emission lines due to absorption of ultraviolet light by gas clouds surrounding new stars.
- As most galaxies are receding from our point of view, their spectra are generally strongly red-shifted.
- Quasars are point sources like stars that emit more radiation than most galaxies and exhibit very large red shifts.
- Spectrum from quasars consists of continuous spectrum plus a few emission lines that fluctuate rapidly in intensity.