2. Many sources (hot, glowing, solid, liquid or high pressure gas) show a continuous spectra across wavebands. Emission spectra Elements in hot gases or plasma produce characteristic bright emission lines (photons) at various wavelengths (according to the energy levels in the atom) 3. Spectroscopy is a vital tool for astronomers and provides a wealth of information Account for the production of emission and absorption spectra and compare these with a continuous blackbody spectrum A spectroscope spreads out light rays to show the colours within the light A black body at the temperature of its surroundings emits as much energy as it absorbs. The emitted radiation has a continuous distribution of wavelengths and depends only on the temperature of the surface of the body. Incandescent bodies, including stars, produce a continuous spectrum like a black body. Like a black body, we can look at the maximum wavelength intensity and predict the temperature. Wein’s Law max T=W max T=W n Absorption spectra –Gas atoms between a continuum source and the observer absorb characteristic wavelengths (according to the difference in energy levels in the atom)

3. Perform a first hand investigation to examine a variety of spectra produced by discharge tubes, reflected sunlight, or incandescent filaments Jacaranda Experiment 15.3

4. n Filters –Pass light over a broad range of wavelengths n Spectrographs –Slit and collimator light parallel beams –dispersing element colours colours –camera and detector (e.g. CCD then data is fed to a computer for analysis) n Spectroscopic surveys –optical fibres can observe several spectra at once Describe the technology needed to measure astronomical spectra A spectroscope spreads out light rays to show the colours within the light Electronic sensors mean that spectroscopy is not just restricted to visible light - also other EMR

5. Identify the general types of spectra produced by stars, emission nebulae, galaxies and quasars

6. Stars n underlying continuous spectra n absorption lines from star atmosphere Identify the general types of spectra produced by stars, emission nebulae, galaxies and quasars Spectral TYPE is based on ABSORPTION spectra

7. Emission Nebulae emission lines in the radio - UV range continuous components Planetary Nebulae strong emission lines - UV,visible,radio waves Supernovae strong emission spectra in visible and UV black body continuum Identify the general types of spectra produced by stars, emission nebulae, galaxies and quasars

8. Normal galaxies have red continuous spectra and calcium absorption lines Galaxies undergoing massive star formation have strong emission lines Active galaxies (with black holes) have broad emission spectra and strong synchrotron radiation Quasars have emission spectra Identify the general types of spectra produced by stars, emission nebulae, galaxies and quasars