Spectroscopy of red variables and other luminous red stars

Long-period variable stars (LPVs) represent the most advanced stage of asymptotic-giant-branch (AGB) evolution prior to planetary-nebula ejection or catastrophic core collapse. In the Magellanic Clouds, through study of the LPVs it has been possible to identify for the first time stars on the AGB with luminosities right up to the AGB limit (Mbol = -7.1), providing direct evidence that the more massive AGB stars produce supernovae. Because the stars have well defined periods, knowledge of the temperature and luminosity enables the mass to be derived. This review highlights spectroscopic observations of the LPVs and discusses the information they provide on nucleosynthesis stars of different mass on the AGB.