Mass Transfer in Stellar Binary Systems Resulting in Peculiar Objects

TYPEAstrophysics Seminar
Speaker:Efrat Sabach
Time:11:30 - 12:30
Location:Lidow 620

Binary interaction has many implication on stellar evolution and might cause an episode of mass transfer or even a change in the stellar mass loss rate itself. Such events can arise from an interaction with even a substellar companion. We suggest that stars whose angular momentum (J) does not increase by a companion, star or planet, along their post-main sequence evolution have much lower mass loss rates along their giant branches. Their classification to a separate group can bring insight on their late evolution stages. We argue that the mass loss rate of J-isolated stars, or Jsolated stars in short, is poorly determined because the mass loss rate expressions on the giant branches are empirically based mainly on stars that experience strong binary interaction. We postulate that the average mass loss rate of Jsolated stars during their giant phases is much lower than of non-Jsolated stars. We find that solar-type Jsolated stars reach higher luminosities and radii on the upper asymptotic giant branch (AGB), and hence are more likely to swallow brown dwarfs and planets during the AGB than traditional calculations predict. This might lead to the formation of elliptical Planetary Nebulae (PNe) and account for bright PNe in old stellar populations.