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| Paper: |
Evolution of Gamma-Ray Burst Progenitors at Low Metallicity |
| Volume: |
353, Stellar Evolution at Low Metallicity: Mass Loss, Explosions, Cosmology |
| Page: |
63 |
| Authors: |
Yoon, S.-C.; Langer, N. |
| Abstract: |
Despite the growing evidence that long Gamma-Ray Bursts (GRBs) are associated with deaths of Wolf-Rayet stars, the evolutionary path of massive stars to GRBs and the exact nature of GRB progenitors remain poorly known. However, recent massive star evolutionary models indicate that — for sufficiently low metallicity — initially very rapidly rotating stars can satisfy the conditions for collapsar formation. Even though magnetic torques are included in these models, a strong core spin-down is avoided through quasi-chemically homogeneous evolution induced by rotational mixing. Here, we explore for which initial mass and spin-range single stars of Z = Zsolar/20 are expected to produce GRBs. We further find a dichotomy in the chemical structure of GRB progenitors, where lower initial masses end their lives with a massive helium envelope which still contains some amounts of hydrogen, while higher initial masses explode with C/O-dominated hydrogen-free atmospheres. |
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