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A&A 465, L29-L33 (2007)
DOI: 10.1051/0004-6361:20077115
Letter
Binary star progenitors of long gamma-ray bursts
M. Cantiello1, S.-C. Yoon2, N. Langer1, and M. Livio31 Institute for Astronomy (IfA)Astronomical Institute, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
e-mail: m.cantiello@astro.uu.nl
2 Astronomical Institute Anton Pannekoek, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
e-mail: scyoon@science.uva.nl
3 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
(Received 17 January 2007 / Accepted 20 February 2007)
Abstract
Context.The collapsar model for long gamma-ray bursts requires a rapidly rotating
Wolf-Rayet star as progenitor.
Aims.We test the idea of producing rapidly rotating Wolf-Rayet stars
in massive close binaries through mass accretion and consecutive
quasi-chemically homogeneous evolution - the latter had previously been shown
to provide collapsars below a certain metallicity threshold.
Methods.We use a 1D hydrodynamic binary evolution code to simulate the evolution of a
16+15 
binary model with an initial orbital period of 5 days and SMC metallicity (Z=0.004).
Internal differential rotation, rotationally induced mixing and magnetic fields are included in both components, as well as non-conservative mass and angular momentum transfer, and tidal spin-orbit coupling.
Results.The considered binary system undergoes early Case B mass transfer.
The mass donor becomes a helium star and dies as a type Ib/c supernova.
The mass gainer is spun-up, and internal magnetic fields efficiently transport accreted angular momentum
into the stellar core.
The orbital widening prevents subsequent tidal synchronization, and the mass gainer
rejuvenates and evolves quasi-chemically homogeneously thereafter.
The mass donor explodes 7 Myr before the collapse of the mass gainer.
Assuming the binary to be broken-up by the supernova kick, the potential
gamma-ray burst progenitor would become a runaway star with a space
velocity of 27
, traveling about 200 pc during its remaining lifetime.
Conclusions.The binary channel presented here does not, as such,
provide a new physical model for collapsar production, as the resulting
stellar models are almost identical to quasi-chemically homogeneously
evolving rapidly rotating single stars. However, it may provide a means
for massive stars to obtain the required high rotation rates.
Moreover, it suggests that a possibly large fraction of long gamma-ray bursts
occurs in runaway stars.
Key words: stars: binaries: general -- stars: rotation -- stars: evolution -- stars: mass-loss -- supernovae: general -- gamma rays: bursts
© ESO 2007