Star Spectra

Star Spectra

1. Continuous Spectra Contain All Possible Frequencies

   • All hot objects emit radiation; hot objects emit a continuous range of frequencies. Hot objects always emit more of one frequency than any other; this wavelength is called the peak frequency. The peak frequency depends on the objects temperature. The higher tge temperatyre the more energy the photons will have meaning a higher peak frequency. The luminosity or brightness also depends on temperature. Blue is hotter than red

2. Light Spectra - Electrons Moving Between Energy Levels

   • An atom contains electrons which move around a tiny positive nucleus. Electrons can only be in certain energy levels around the nucleus [lower energy levels are nearer to the nucleus]. Electons move between energy levels if they lose or gain energy. Electrons can be given enough energy to be removed from the atom this is called ionisation
   • ABSORPTION SPECTRA: Since electrons need a specific amount of energy to go into the next shell they only absorb a specific frequency light. This can be seen as a colourful spectrum with black lines where the electron has absorbed energy
   • EMISSION SPECTRA: Electrons are unstable at higher energy levels so they release energy by emitting radiation of a particular frequency. This cn be seen as a series of bright lines on a black chart

3. Astronomers use spectra to work out what stars are made of

   • Energy levels in atoms are different for each element - so each element has its own light spectrum. The photosphere of a star emits a continuous spectrum of radiation by looking at the position of the lines you can work out what chemical elements are present in the stars atmosphere