The width of the lines in a spectrum of an object can indicate either the temperature of the emitting region or it can give the range of velocities found within the emitting region. A number of galaxies have particularly wide lines in their spectra. If the broad lines are attributed to high temperatures, these are much greater than found in normal galaxies and resemble the temperatures found in supernova remnants. Alternatively, the line widths could indicate the velocity dispersion within the nuclei of these galaxies. This might imply that clouds of gas are moving about rapidly (up to 5000 km s-1) within the nuclei of these galaxies. However, with such high speeds the clouds could only be bound gravitationally to the nucleus if it was extremely massive. Otherwise the clouds must be moving rapidly away from the nuclear region and we may have to consider the possibility that they have been ejected from the nucleus of the galaxy.

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