Volume 478, Number 3, February II 2008
|Page(s)||769 - 778|
|Section||Interstellar and circumstellar matter|
|Published online||04 December 2007|
The circumstellar medium around a rapidly rotating, chemically homogeneously evolving, possible gamma-ray burst progenitor
Astronomical Institute, Utrecht University, PO Box 80000, 3508 TA, Utrecht, The Netherlands e-mail: [A.vanMarle;N.Langer]@astro.uu.nl
2 Bartol Research Institute, University of Delaware, 102 Sharp Laboratory, Newark, 19716 DE, Delaware, USA e-mail: email@example.com
3 Astronomical Institute “Anton Pannekoek”, University of Amsterdam, Kruislaan 403, 1098 SJ, Amsterdam, The Netherlands e-mail: firstname.lastname@example.org
4 Instituto de Astronomía-UNAM, APDO Postal 877, Ensenada, 22800 Baja California, Mexico e-mail: email@example.com
Accepted: 30 October 2007
Context.Rapidly rotating, chemically homogeneously evolving massive stars are considered to be progenitors of long gamma-ray bursts.
Aims.We present numerical simulations of the evolution of the circumstellar medium around a rapidly rotating 20 star at a metallicity of . Its rotation is fast enough to produce quasi-chemically homogeneous evolution. While conventionally, a star of 20 would not evolve into a Wolf-Rayet stage, the considered model evolves from the main sequence directly to the helium main sequence.
Methods.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.
Results.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.
Conclusions.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 density profile normally associated with stellar winds close to the star.
Key words: gamma-rays: bursts / hydrodynamics / ISM: bubbles / stars: winds, outflows / stars: Wolf-Rayet
© ESO, 2008
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.