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Here we present the discovery of three unusual long-term variables found inthe Digital Access to a Sky Century at Harvard (DASCH) project, with ~1magnitude variations in their lightcurves on ~10-100 yr timescales. They areall spectroscopically identified as K2III giant stars, probably in the thickdisk. Their lightcurves do not match any previously measured for known types ofvariable stars, or any theoretical model reported for red giants, and insteadsuggest a new dust formation mechanism or the first direct observation of"short" timescale evolution-driven variability. More theoretical work on thelithium flash near the Red Giant Branch (RGB) bump and the helium shellignition in the lower Asymptotic Giant Branch (AGB), as well as long termmonitoring of K2III thick disk stars is needed.

DASCH Discovery of Large Amplitude ~10-100 Year Variability in K Giants