An Interacting Binary System Powers Precessing Outflows of an Evolved Star

TL;DR

This paper presents evidence that binary star interactions, specifically a precessing accretion disk around a companion star, drive the asymmetric, precessing outflows observed in evolved stars like Fleming 1, explaining their non-spherical envelopes.

Contribution

It provides observational confirmation of a binary interaction model involving a precessing accretion disk causing asymmetric outflows in evolved stars.

Findings

Discovery of a post common-envelope binary nucleus in Fleming 1.

Confirmation that binary interactions can produce precessing outflows.

Supports the hypothesis that binary systems explain non-spherical planetary nebulae.

Abstract

Stars are generally spherical, yet their gaseous envelopes often appear non-spherical when ejected near the end of their lives. This quirk is most notable during the planetary nebula phase when these envelopes become ionized. Interactions among stars in a binary system are suspected to cause the asymmetry. In particular, a precessing accretion disk around a companion is believed to launch point-symmetric jets, as seen in the prototype Fleming 1. Our discovery of a post common-envelope binary nucleus in Fleming 1 confirms that this scenario is highly favorable. Similar binary interactions are therefore likely to explain these kinds of outflows in a large variety of systems.