Gaia EDR3 Data of Post-AGB Stars with Overabundance of s-process Elements: Evolutionary Status and Binarity

Abstract

Kamath et al. analyzed Gaia EDR3 data of 18 post-asymptotic giant branch (AGB) supergiants having overabundance of s-process elements, some of which exhibit unusually low luminosities in disagreement with expectations of s-process nucleosynthesis. I have examined the Gaia RUWE statistics of these stars, and find that 13 have RUWE ≫ 1.4, suggesting they are most likely unresolved binaries that contain low-mass companions. The remaining five stars have RUWE < 1.4 and I find that their luminosities are in agreement with post-AGB evolutionary tracks.