Letter to the Editor
Wind anisotropies and GRB progenitors
Geneva Observatory, University of Geneva, 1290 Sauverny, Switzerland e-mail: [andre.maeder;georges.meynet]@obs.unige.ch
Accepted: 10 January 2007
Aims.We study the effect of wind anisotropies on the stellar evolution leading to collapsars.
Methods.Rotating models of a 60 star with on the ZAMS, accounting for shellular rotation and a magnetic field, with and without wind anisotropies, are computed at until the end of the core He-burning phase.
Results.Only the models accounting for the effects of the wind anisotropies retain enough angular momentum in their core to produce a Gamma Ray Burst (GRB). The chemical composition is such that a type Ic supernova event occurs.
Conclusions.Wind anisotropies appear to be a key physical ingredient in the scenario leading to long GRBs.
Key words: stars: evolution / stars: rotation / stars: magnetic fields / gamma rays: bursts
© ESO, 2007