Journal Article

A mid-infrared imaging catalogue of post-asymptotic giant branch stars*

Eric Lagadec, Tijl Verhoelst, Djamel Mékarnia, Olga Suárez, Albert A. Zijlstra, Philippe Bendjoya, Ryszard Szczerba, Olivier Chesneau, Hans Van Winckel, Michael J. Barlow, Mikako Matsuura, Janet E. Bowey, Silvia Lorenz-Martins and Tim Gledhill

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 417, issue 1, pages 32-92
Published in print October 2011 | ISSN: 0035-8711
Published online October 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2011.18557.x
A mid-infrared imaging catalogue of post-asymptotic giant branch stars*

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Post-asymptotic giant branch (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 AGB towards the planetary nebula stage. There is growing evidence 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 VLT spectrometer and imager for the mid-infrared (VISIR)/VLT, T-Recs/Gemini-South and Michelle/Gemini-North. We found that all 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 into two categories. (i) The nebulae with a dense central core, that are either bipolar and multipolar and (ii) the nebulae with no central core, with an elliptical morphology. The dense central torus observed likely hosts binary systems which triggered fast outflows that shaped the nebulae.

Keywords: circumstellar matter; infrared: stars

Journal Article.  14279 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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