# The large-scale nebular pattern of a superwind binary in an eccentric orbit

## TL;DR

This paper presents high-resolution observations of AFGL 3068, revealing how an eccentric binary orbit influences the large-scale spiral-shell pattern in a transitioning star, providing insights into binary star interactions.

## Contribution

It demonstrates that the circumstellar spiral-shell pattern is shaped by an eccentric binary orbit, offering new understanding of mass-loss dynamics in evolved stars.

## Key findings

- Eccentric binary orbit influences nebular morphology.
- Spiral-shell pattern observed at thousands of AU from the star.
- Provides evidence linking binary interactions to nebular structures.

## Abstract

Preplanetary nebulae and planetary nebulae are evolved, mass-losing stellar objects that show a wide variety of morphologies. Many of these nebulae consist of outer structures that are nearly spherical (spiral/shell/arc/halo) and inner structures that are highly asymmetric (bipolar/multipolar). The coexistence of such geometrically distinct structures is enigmatic because it hints at the simultaneous presence of both wide and close binary interactions, a phenomenon that has been attributed to stellar binary systems with eccentric orbits. Here we report new high-resolution molecular-line observations of the circumstellar spiral-shell pattern of AFGL 3068, an asymptotic giant branch star transitioning to the preplanetary nebula phase. The observations clearly reveal that the dynamics of the mass loss is influenced by the presence of an eccentric-orbit binary. This quintessential object opens a new window on the nature of deeply embedded binary stars through the circumstellar spiral-shell patterns that reside at distances of several thousand Astronomical Units from the stars.