Query : 2008A&A...478..769V

2008A&A...478..769V - Astronomy and Astrophysics, volume 478, 769-778 (2008/2-2)

The circumstellar medium around a rapidly rotating, chemically homogeneously evolving, possible gamma-ray burst progenitor.


Abstract (from CDS):

Rapidly rotating, chemically homogeneously evolving massive stars are considered to be progenitors of long gamma-ray bursts. We present numerical simulations of the evolution of the circumstellar medium around a rapidly rotating 20M star at a metallicity of Z=0.001. Its rotation is fast enough to produce quasi-chemically homogeneous evolution. While conventionally, a star of 20M would not evolve into a Wolf-Rayet stage, the considered model evolves from the main sequence directly to the helium main sequence. We use the time-dependent wind parameters, such as mass loss rate, wind velocity and rotation-induced wind anisotropy from the evolution model as input for a 2D hydrodynamical simulation. While the outer edge of the pressure-driven circumstellar bubble is spherical, the circumstellar medium close to the star shows strong non-spherical features during and after the periods of near-critical rotation. We conclude that the circumstellar medium around rapidly rotating massive stars differs considerably from the surrounding material of non-rotating stars of similar mass. Multiple blue-shifted high velocity absorption components in gamma-ray burst afterglow spectra are predicted. As a consequence of near critical rotation and short stellar evolution time scales during the last few thousand years of the star's life, we find a strong deviation of the circumstellar density profile in the polar direction from the 1/R2 density profile normally associated with stellar winds close to the star.

Abstract Copyright:

Journal keyword(s): gamma-rays: bursts - hydrodynamics - ISM: bubbles - stars: winds, outflows - stars: Wolf-Rayet

Simbad objects: 2

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Number of rows : 2
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
1 GRB 021004 gB 00 26 54.68 +18 55 41.6           ~ 548 0
2 SN 1987A SN* 05 35 28.020 -69 16 11.07           SNIIpec 4957 2

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