Predicting the Evolutionary Descendents of Sequence E Stars

Abstract

Sequence E variables are close binary red giants that show ellipsoidal light variations. They are likely to terminate their red giant evolution by a common envelope (CE) event when the red giant fills its Roche lobe, and produce close binary Planetary Nebulae (PNe). We made a Monte Carlo simulation to predict the fraction of Planetary Nebulae Nuclei (PNNe) that are post-CE binaries, using the observed frequency of sequence E binaries in the LMC to normalize our calculations. We find that 10-16% of PNNe should be short period, post-CE binaries.