High-Speed Outflows and Dusty Disks during the AGB to PN Transition: The PANORAMA survey

TL;DR

This survey uses high-resolution ALMA observations to study the complex outflows and disks in post-AGB stars transitioning to planetary nebulae, revealing bipolar structures and symmetry that inform models of nebula shaping.

Contribution

It provides detailed high-angular-resolution observations of outflows and disks in post-AGB objects, advancing understanding of the physical mechanisms in nebula evolution.

Findings

Detection of bipolar and multipolar high-velocity outflows.

Presence of dense toroidal waists and circular rings.

High degree of point-symmetry in mass ejecta morphology.

Abstract

As mass-losing asymptotic giant branch (AGB) stars evolve to planetary nebulae (PNe), the mass outflow geometries transform from nearly spherical to extreme aspherical. The physical mechanisms governing this transformation are widely believed to be linked to binarity and the associated production of disks and fast jets during transitional (post-AGB) evolutionary stages. We are carrying out a systematic ALMA survey ($P$re-planet$A$ry $N$ebulae high-angular-res$O$lution su$R$vey with $A$L$MA$ or PANORAMA) of a representative sample of bipolar and multipolar post-AGB objects. We have obtained high angular-resolution (0".1-0".4) observations of the CO(3--2) and/or 6--5 emission in order to probe the spatio-kinematic structure of the collimated outflows and the central disk/torii. The results are remarkable, generally showing the presence of bipolar or multipolar high-velocity outflows, dense toroidal waists, and in one case, a geometrically-thin circular ring around the central bipolar nebula. A high degree of point-symmetry characterizes the morphology of the mass ejecta. In this contribution, we present these and other highlights from our survey. We aim to use 2D/3D radiative transfer modeling in order to derive accurate outflow momenta, masses and mass-loss rates for our sample, and build hydrodynamical models that can explain the observed spatio-kinematic structures. These results will then be used to distinguish between different classes of PN-shaping binary interaction models.