Aims. Analysis of the innermost regions of the carbon-rich star IRC+10216 and of the outer layers of its circumstellar envelope have been performed in order to constrain its mass-loss history. Methods. We analyzed the high dynamic range of near-infrared adaptive optics and the deep V-band images of the circumstellar envelope of IRC+10216 using high angular resolution, collected with the VLT/NACO and FORS1 instruments. Results. From the near-infrared observations, we present maps of the sub-arcsecond structures, or clumps, in the innermost regions. The morphology of these clumps is found to strongly vary from J-to L-band. Their relative motion appears to be more complex than proposed in earlier works: they can be weakly accelerated, have a constant velocity, or even be motionless with respect to one another. From V-band imaging, we present a high spatial resolution map of the shell distribution in the outer layers of IRC+10216. Shells are resolved well up to a distance of about 90 to the core of the nebula and most of them appear to be composed of thinner elongated shells. Finally, by combining the NACO and FORS1 images, a global view is present to show both the extended layers and the bipolar core of the nebula together with the real size of the inner clumps. Conclusions. This study confirms the rather complex nature of the IRC+10216 circumstellar environment. In particular, the coexistence at different spatial scales of structures with very different morphologies (clumps, bipolarity, and almost spherical external layers) is very puzzling. This confirms that the formation of AGB winds is far more complex than usually assumed in current models.

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.

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