OBSCURED ASYMPTOTIC GIANT BRANCH STARS IN THE MAGELLANIC CLOUDS - IV - CARBON STARS AND OH IR STARS/

We present N-band photometry for a sample of 21 dust-enshrouded AGB st ars in the Large Magellanic Cloud, and three additional sources in the Small Magellanic Cloud. Together with near-infrared photometry, this is used to give a tentative classification into carbon and oxygen-rich atmospheres. Bolometric luminosities are also estimated for these sta rs. In addition, we present the results of a survey for OH masers in t he LMC, which resulted in the discovery of OH maser emission from IRAS 04407-7000. Spectra between 600 and 1000 nm have been obtained for two heavily obscured AGB stars in the LMC, confirming them to be highly r eddened very late M-type giants. Because the dust-enshrouded stars are clearly undergoing heavy mass loss they are assumed to be very near t he termination of their respective Asymptotic Giant Branch phases. The fraction of mass-losing carbon stars decreases with increasing lumino sity, as expected from Hot Bottom Burning. The best candidate carbon s tar, with M-bol similar to -6.8 mag, is the most luminous mass-losing carbon star in the Magellanic Clouds, and amongst the most luminous AG B stars. At lower luminosities (M-bol similar to -5 mag) both oxygen a nd carbon stars are found. This may be explained by a range in metalli city of the individual mass-losing AGB stars.