A rotating spiral structure in the innermost regions around IRC+10216

G. Quintana-Lacaci, J. Cernicharo, M. Agúndez, L. Velilla Prieto, A. Castro-Carrizo, N. Marcelino, C. Cabezas, I. Peña, J.L. Alonso, J. Zuñiga, A. Requena, A. Bastida, Y. Kalugina, F. Lique, M. Guélin. 2016. A rotating spiral structure in the innermost regions around IRC+10216. 11th Pacific Rim Conference on Stellar Astrophysics – Physics and Chemistry of the Late Stages of Stellar Evolution, 728, DOI: 10.1088/1742-6596/728/2/022005

ALMA interferometer is providing us molecular maps with unprecedent precision and sensitivity, Key processes in the ejection of matter and dust from these objects occur in their inner zones. We have obtained sub-arcsecond interferometric maps of rotational transitions of metal-bearing molecules towards the prototypical C-rich evolved star IRC+ 10216. While Albearing molecular emission presents a roughly spherical shell, the molecular emission from NaCl and KCl presents an elongation in the inner regions, with a central minimum. The presence of the observed features only in KCl and NaCl might be a direct result of their comparatively high dipole moment with respect to the Al-bearing species. The most plausible interpretation for the spatial distribution of the salts is a spiral with a NaCl mass of 0.08 M-circle dot with an inner radius of 27 AU. The gas kinematics suggests that it is slowly expanding and rotating. Alternative gas distributions which could result in the presence of the elongation are also explored.

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