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Issue A&A
Volume 464, Number 2, March III 2007
Page(s) L11 - L15
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20066509



A&A 464, L11-L15 (2007)
DOI: 10.1051/0004-6361:20066509

Letter

Wind anisotropies and GRB progenitors

G. Meynet and A. Maeder

Geneva Observatory, University of Geneva, 1290 Sauverny, Switzerland
    e-mail: [andre.maeder;georges.meynet]@obs.unige.ch

(Received 5 October 2006 / Accepted 10 January 2007)

Abstract
Aims.We study the effect of wind anisotropies on the stellar evolution leading to collapsars.
Methods.Rotating models of a 60 $M_\odot$ star with $\Omega/\Omega_{\rm crit}=0.75$ on the ZAMS, accounting for shellular rotation and a magnetic field, with and without wind anisotropies, are computed at Z=0.002 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


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