Close binary central stars and the abundance discrepancy - new extreme objects

TL;DR

This study links extreme abundance discrepancies in planetary nebulae to the presence of close binary central stars, discovering new extreme cases and suggesting a strong association between the two phenomena.

Contribution

It provides new spectral data of nebulae with close binary stars and identifies several new extreme abundance discrepancy objects, strengthening the connection between binarity and abundance anomalies.

Findings

High fraction of nebulae with close binaries show extreme abundance discrepancies

No non-extreme discrepancies found in the sample

Supports the hypothesis that close binary stars influence nebular abundance anomalies

Abstract

Recent work (Corradi et al. 2015, Jones et al. 2016) has shown that the phenomenon of extreme abundance discrepancies, where recombination line abundances exceed collisionally excited line abundances by factors of 10 or more, seem to be strongly associated with planetary nebulae with close binary central stars. To further investigate, we have obtained spectra of a sample of nebulae with known close binary central stars, using FORS2 on the VLT, and we have discovered several new extreme abundance discrepancy objects. We did not find any non-extreme discrepancies, suggesting that a very high fraction of nebulae with close binary central stars also have an extreme abundance discrepancy.