AGB stars are stars with a mass below approximately 8 M_sun that have evolved through the Red Giant phase and the Horizontal Branch phase and are now red giants again - for the last time.  They rapidly rise in luminosity, but when their luminosity exceeds a certain limit they begin to pulsate and to loose matter at ultimately a rate between 10^-6 and 10^-4 M_sun/yr; this process continues until all the matter surrounding the core has been ejected. The stars then turn into a planetary nebula, and ultimately the core will remain as a cooling white dwarf. AGB stars have been detected in globular clusters, and this shows that some AGB stars can be as old as 10¹² yr, whereas the youngest (and most luminous) AGB stars are perhaps not older than 100 Myr. I plan to review some of the new observational evidence on the properties of the AGB stars.

AGB stars can be detected inside our Milky Way Galaxy and in most galaxies of the Local Group. I want to discuss the presence of AGB stars in our and in other galaxies and what may be derived about the stellar populations of which these AGB stars are members, e.g. information about the star formation history or the mergers in the past.
 
 

Jan Palous