Light variability of color selected IRAS sources: variables in late AGB and early post-AGB phase

Abstract

The transition from AGB to post-AGB stars was investigated using the H-band monitoring of these objects for four years. The Mira-type pulsations were found only in the restricted area in the IRAS two color diagram. The non-variable sources occupy the region close to the AGB variables. A new class of post-AGB variables was discovered beyond the non-variables. They are probably crossing the instability strip on their rapid evolution to the planetary nebula stage.