A&A 452, 257-268 (2006)
DOI: 10.1051/0004-6361:20054739

Imaging the circumstellar envelopes of AGB stars

N. Mauron¹ and P. J. Huggins<sup>2

1</sup>  Groupe d'Astrophysique, UMR 5024 CNRS, Case CC72, Place Bataillon, 34095 Montpellier Cedex 5, France
    e-mail: mauron@graal.univ-montp2.fr
²  Physics Department, New York University, 4 Washington Place, New York NY 10003, USA

(Received 21 December 2005 / Accepted 21 February 2006 )

Abstract
Aims.We report the results of an exploratory program to image the extended circumstellar envelopes of asymptotic giant branch (AGB) stars in dust-scattered galactic light. The goal is to characterize the morphology of the envelopes as a probe of the mass-loss process.
Methods.The observations consist of short exposures with the VLT and longer exposures with 1-2 m telescopes, augmented with archival images from the Hubble Space Telescope.
Results.We observed 12 AGB stars and detected the circumstellar envelopes in 7. The detected envelopes have mass loss rates   yr^-1, and they can be seen out to distances  kpc. The observations provide information on the mass loss history on time scales up to  yr. For the five AGB envelopes in which the circumstellar geometry is well determined by scattered light observations, all except one (OH348.2-19.7) show deviations from spherical symmetry. Two (IRC+10216 and IRC+10011) show roughly spherical envelopes at large radii but asymmetry or bipolarity close to the star; one (AFGL 2514) shows an extended, elliptical envelope, and one (AFGL 3068) shows a spiral pattern. The non-spherical structures are all consistent with the effects of binary interactions.
Conclusions.Our observations are in accord with a scenario in which binary companions play a role in shaping planetary nebulae, and show that the circumstellar gas is already partly shaped on the AGB, before evolution to the proto-planetary nebula phase.

Key words: stars: AGB and post-AGB - stars: mass-loss - stars: circumstellar matter -- stars: late-type

SIMBAD Objects

© ESO 2006

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

• If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
• You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
• You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.