A mid-infrared imaging catalogue of post-AGB stars

TL;DR

This study presents a mid-infrared imaging catalogue of 93 post-AGB stars, revealing diverse nebular morphologies and providing insights into the role of binary interactions in shaping planetary nebulae.

Contribution

It offers the first systematic mid-infrared imaging survey of post-AGB stars, highlighting the prevalence of non-spherical nebulae and the potential influence of binary systems.

Findings

All resolved proto-planetary nebulae show asymmetry.

Resolved nebulae are either bipolar/multipolar or elliptical.

Dense central tori likely host binary systems that influence nebular shaping.

Abstract

Post-AGB stars are key objects for the study of the dramatic morphological changes of low- to intermediate-mass stars on their evolution from the Asymptotic Giant Branch (AGB) towards the Planetary Nebula stage. There is growing evidences that binary interaction processes may very well have a determining role in the shaping process of many objects, but so far direct evidence is still weak. We aim at a systematic study of the dust distribution around a large sample of Post-AGB stars as a probe of the symmetry breaking in the nebulae around these systems. We used imaging in the mid-infrared to study the inner part of these evolved stars to probe direct emission from dusty structures in the core of Post-AGB stars in order to better understand their shaping mechanisms. We imaged a sample of 93 evolved stars and nebulae in the mid-infrared using VISIR/VLT, T-Recs/Gemini South and Michelle/Gemini North. We found that all the the Proto-Planetary Nebulae we resolved show a clear departure from spherical symmetry. 59 out of the 93 observed targets appear to be non resolved. The resolved targets can be divided in two categories. The nebulae with a dense central core, that are either bipolar and multipolar. The nebulae with no central core have an elliptical morphology.The dense central torus observed likely host binary systems which triggered fast outflows that shaped the nebulae.