Institute of Astronomy

Hydrodynamics of the Common Envelope Phase in High Resolution

SpeakerTalk DateTalk Series
Sebastian Ohlmann26 July 2016Binary Stars Talks

Abstract

The common envelope (CE) phase is important for the evolution of close binary systems with compact stars.  Here, I present high-resolution hydrodynamics simulations of the CE phase of a two solar mass red giant interacting with different companions. The simulations employ the moving-mesh code AREPO that uses an unstructured, adaptive grid that moves with the fluid.  I will show that shear flows in the envelope lead to large-scale instabilities indicating the onset of convection. A resolution study shows in combination with an analysis of the angular momentum and energy transport that high resolutions are necessary for converged results.  Moreover, I will present results from the first magnetohydrodynamic simulations of the CE phase. These show that a dynamical amplification of magnetic fields is possible, saturating at fields of tens of kilogauss in the envelope. The dynamical impact of the magnetic fields on the evolution, however, is small on the simulated timescales.

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