A Study of Multiple-Mode Pulsating Red Giants
  This project began as a search for triple-mode pulsating red giants (PRGs) among known double-mode PRGs,, using AAVSO visual data. It then expanded to include a check on the reality and significance of some double-mode PRGs. We identified several "double-mode" PRGs in which one of the periods might simply be an alias of the other. We also comment on the possibility that the additional periods might be harmonics, rather than overtones. As for the triple-mode pulsators: in our sample, we find no convincing cases in which there is a significant, non-alias third period which might be an additional radial period. We note, however, that a few triple-mode pulsators have been found in a very large sample of PRGs in the LMC/ We discuss the results in the context of recent theoretical models of pulsating red giants. 
John R. Percy and Tanya Brekelmans
astro-ph.SR