The shock-heated atmosphere of an asymptotic giant branch star resolved by ALMA
Journal article, 2017

Our current understanding of the chemistry and mass-loss processes in Sun-like stars at the end of their evolution depends critically on the description of convection, pulsations and shocks in the extended stellar atmosphere 1 . Three-dimensional hydrodynamical stellar atmosphere models provide observational predictions 2 , but so far the resolution to constrain the complex temperature and velocity structures seen in the models has been lacking. Here we present submillimetre continuum and line observations that resolve the atmosphere of the asymptotic giant branch star W Hydrae. We show that hot gas with chromospheric characteristics exists around the star. Its filling factor is shown to be small. The existence of such gas requires shocks with a cooling time longer than commonly assumed. A shocked hot layer will be an important ingredient in current models of stellar convection, pulsation and chemistry at the late stages of stellar evolution.


Wouter Vlemmings

Astronomy and Plasmaphysics

Theo Khouri

Astronomy and Plasmaphysics

Eamon O Gorman

Dublin Institute for Advanced Studies

Elvire De Beck

Astronomy and Plasmaphysics

E. Humphreys

European Southern Observatory (ESO)

Boy Lankhaar

Astronomy and Plasmaphysics

Matthias Maercker

Astronomy and Plasmaphysics

Hans Olofsson

Astronomy and Plasmaphysics

S. Ramstedt

Uppsala University

Daniel Tafoya Martinez

Astronomy and Plasmaphysics

A. Takigawa

Kyoto University

Nature Astronomy

23973366 (eISSN)

Vol. 1 12 848-853

Magnetic fields and the outflows during the formation and evolution of stars (OUTFLOWMAGN)

European Commission (EC) (EC/FP7/614264), 2014-05-01 -- 2019-04-30.

Subject Categories

Astronomy, Astrophysics and Cosmology


Basic sciences


Onsala Space Observatory



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