Dust Enshrouded AGB Variables in the LMC

The luminosities and periods of obscured AGB stars in the LMC are discussed using a combination of ISO and ground-based infrared photometry. The bolometric luminosities of these stars fall close to an extrapolation of the period-luminosity relation derived for oxygen-rich Mira variables, with both oxygen- and carbon-rich stars falling close to the same relation. It has been known for many years that there are, in the Magellanic Clouds, significant numbers of large amplitude variables which have considerably higher luminosities than the period-luminosity relation would predict. Many of these can be shown to be undergoing hot bottom burning. It is speculated that all large amplitude AGB stars with luminosities significantly higher than indicated by the period-luminosity relation are undergoing hot bottom burning.