ESO DOI Service

• Paladini, Claudia [Institut d’Astronomie et d’Astrophysique, Université libre de Bruxelles, Belgium]
• Klotz, Daniela [Department of Astrophysics, University of Vienna, Austria]
• Sacuto, Stephane [Department of Astrophysics, University of Vienna, Austria; Department of Physics and Astronomy, Division of Astronomy and Space Physics, University of Uppsala, Sweden]
• Lagadec, Eric [Laboratoire Lagrange, Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Nice, France]
• Wittkowski, Markus [European Southern Observatory (ESO)]
• Richichi, Andrea [National Astronomical Research Institute of Thailand, Chiang Mai, Thailand]
• Hron, Josef [Department of Astrophysics, University of Vienna, Austria]
• Jorissen, Alain [Institut d’Astronomie et d’Astrophysique, Université libre de Bruxelles, Belgium]
• Groenewegen, Martin A. T. [Koninklijke Sterrenwacht van België, Brussel, Belgium]
• Kerschbaum, Franz [Department of Astrophysics, University of Vienna, Austria]
• Verhoelst, Tijl [Belgian Institute for Space Aeronomy, Brussels, Belgium]
• Rau, Gioia [Department of Astrophysics, University of Vienna, Austria]
• Olofsson, Hans [Department of Earth and Space Sciences, Onsala Space Observatory, Sweden]
• Zhao-Geisler, Ronny [Department of Earth Sciences, National Taiwan Normal University, Taipei, Taiwan]
• Matter, Alexis [Laboratoire Lagrange, Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Nice, France]

The Mid-infrared Interferometric instrument (MIDI) at the Very Large Telescope Interferometer (VLTI) has been used to spatially resolve the dust-forming region of 14 asymptotic giant branch (AGB) stars with different chemistry (O-rich and C-rich) and variability types (Miras, semi-regular, and irregular variables). The main goal of the programme was to detect deviations from spherical symmetry in the dust-forming region of these stars. All the stars of the sample are well resolved with the VLTI, and five are asymmetric and O-rich. This finding contrasts with observations in the near-infrared, where the C-rich objects are found to be more asymmetric than the O-rich ones. The nature of the asymmetric structures so far detected (dusty discs versus blobs)remains uncertain and will require imaging on milli-arcsecond scales.