Presupernova Evolution of Rotating Massive Stars. I. Numerical Method and Evolution of the Internal Stellar Structure

Abstract

The evolution of rotating stars with zero-age main sequence (ZAMS) masses in the range 8 M ⊙ to 25 M ⊙ is followed through all stages of stable evolution. The initial angular momentum is chosen such that the star's equatorial rotational velocity on the ZAMS ranges from zero to ∼ 70 % of break-up. The stars rotate rigidly on the ZAMS as a consequence of angular momentum redistribution during the pre-main sequence evolution. Redistribution of angular momentum and chemical species are then followed as a consequence of Eddington-Sweet circulation, the Solberg-Høiland instability, the Goldreich-Schubert-Fricke instability, and secular and dynamic shear instability. The effects of the centrifugal force on the stellar structure are included. Convectively unstable zones are assumed to tend towards rigid rotation and uncertain mixing efficiencies are gauged by observations. We find, as noted in previous work, that rotation increases the helium core masses and enriches the stellar envelopes with products of hydrogen burning. We determine, for the first time, the angular momentum distribution in typical presupernova stars along with their detailed chemical structure. Angular momentum loss due to (non-magnetic) stellar winds and the redistribution of angular momentum during core hydrogen burning are of crucial importance for the specific angular momentum of the core. Neglecting magnetic fields, we find angular momentum transport from the core to the envelope to be unimportant after core helium burning. We obtain specific angular momenta for the iron core and overlaying material of 10 16 . . . 10 17 erg s. These values are insensitive to the initial angular momentum and to uncertainties in the efficiencies of rotational mixing. They are small enough to avoid triaxial deformations of the iron core before it collapses, but could lead to neutron stars which rotate close to break-up. They are also in the range required for the collapsar model of gamma-ray bursts. The apparent discrepancy with the measured rotation rates of young pulsars is discussed.

Ultra-stripped supernovae: progenitors and fate

“…For the electron conduction opacity, we follow Hubbard & Lampe (1969) in the non-relativistic case, and Canuto (1970) in the relativistic case. The stellar models are computed using extended nuclear networks (Heger et al 2000). Our helium stars are calculated for a metallicity of Z = 0.02 (mainly isotopes of C, N, O and Ne).…”

Pair‐Instability Supernovae, Gravity Waves, and Gamma‐Ray Transients

“…The evolution of these stars was followed from central hydrogen ignition until core collapse using a one-dimensional hydrodynamic stellar evolution code, KEPLER (Weaver, Zimmerman, & Woosley 1978). Stellar rotation (constant along shells) was included as described in Heger, Langer, & Woosley (2000). That is, mixing and redistribution of angular momentum induced by convection, shear, Eddington-Sweet circulation, etc., were followed, but the centrifugal force terms were not included in the stellar structure equations.…”

Systematic features of axisymmetric neutrino-driven core-collapse supernova models in multiple progenitors

“…Up to now, the number of these stateof-the-art models amounts to ∼ 40 covering the zero-age main sequence (ZAMS) mass from 8.1 M ⊙ (Müller et al 2012a) to 27 M ⊙ (Hanke et al 2013). Based on stellar evolutionary calculations, on the other hand, hundreds of CCSN progenitors are available now, depending on a wide variety of the ZAMS mass, metallicity, rotation, and magnetic fields (e.g., Nomoto & Hashimoto 1988;Woosley & Weaver 1995;Woosley et al 2002;Woosley & Heger 2007;Heger et al 2000;Heger [Vol. , et al 2005;Limongi & Chieffi 2006).…”