Volume 558, October 2013
|Number of page(s)||7|
|Section||Interstellar and circumstellar matter|
|Published online||14 October 2013|
Magnetohydrodynamics of Mira’s cometary tail
Department of Chemistry and Physics, Western Carolina University, Cullowhee, North Carolina 28723, USA
Received: 14 June 2013
Accepted: 26 July 2013
Aims. The asymptotic giant-branch, long-period variable star Mira exhibits a 4 parsec long cometary tail in the far-ultraviolet. We address the issue of the origin of this structure and its emission process by simulating the transition of this star from the interstellar medium to the Local Bubble, which is a tenuous, high-pressure medium.
Methods. We use the hydrodynamic and the magnetohydrodynamic modules of the PLUTO astrophysical code to carry out our simulations. We study the system without a cooling function, with a simplified exponential cooling function, and with a simplified nonequilibrium cooling function.
Results. We find evidence that magnetohydrodynamics constrain the shape of the cometary tail and explain features of its far-ultraviolet emission. We suggest an emission process that involves C0 excitation through inelastic electron collisions and a two-photon continuum to explain the luminosity of Mira’s tail.
Key words: radiation mechanisms: thermal / stars: AGB and post-AGB / ISM: magnetic fields / methods: numerical / shock waves / ISM: jets and outflows
© ESO, 2013
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.