Resolving the Extended Atmosphere and Inner Wind of Mira (omicron Ceti) with the ALMA Long Baseline

Ka Tat Wong, Tomasz Kaminski, Karl M. Menten & Friedrich Wyrowski

Max Planck Institute for Radio Astronomy, Germany

We present recent ALMA data of Mira (omi Cet) which show its radio photosphere and inner wind at an unprecedented detail. Observations were obtained in the 2014 ALMA Long Baseline Campaign with baselines up to 15 km and produced maps of SiO and H₂O emission/absorption at an angular resolution of ~30 mas at 220 GHz. They clearly resolve the wind of this prototypical Mira variable within the dust condensation radius. Very unique in the dataset is that transition lines are seen in *absorption* towards the continuum source, even in lines which are dominated by maser emission, allowing detailed studies of physical conditions and chemistry along the line of sight. We have modelled the 28SiO J=5-4 v=0,1,2 and H₂O v₂=1 J(Ka,Kc)=5(5,0)-6(4,3) emission and absorption with the aim to constrain the spatial structures, dust condensation process, shock dissipation and the kinematics. The results challenge previous hydrodynamic and dust-formation models of Mira and Mira variables.

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