Slowing the spins of stellar cores

By J. Fuller, A. Piro, Adam S. Jermyn. Monthly notices of the Royal Astronomical Society, 2019

211 citations recorded by the source corpus.

The angular momentum (AM) evolution of stellar interiors, along with the resulting rotation rates of stellar remnants, remains poorly understood. Asteroseismic measurements of red giant stars reveal that their cores rotate much faster than their surfaces, but much slower than theoretically predicted, indicating an unidentified source of AM transport operates in their radiative cores. Motivated by this, we investigate the magnetic Tayler instability and argue that it saturates when turbulent dissipation of the perturbed magnetic field energy is equal to magnetic energy generation via winding. This leads to larger magnetic field amplitudes, more efficient AM transport, and smaller shears than predicted by the classic Tayler–Spruit dynamo. We provide prescriptions for the effective AM diffusivity and incorporate them into numerical stellar models, finding they largely reproduce (1) the nearly rigid rotation of the Sun and main sequence stars, (2) the core rotation rates of low-mass red giants during hydrogen shell and helium burning, and (3) the rotation rates of white dwarfs. We discuss implications for stellar rotational evolution, internal rotation profiles, rotational mixing, and the spins of compact objects.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/cb5247751cbeb7cb16cae3be5fd12fe5a8adaca9

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Citations in the corpus

Most Black Holes Are Born Very Slowly Rotating (2019, methodology): “However, similar to the results of Fuller et al. (2019) for low-mass stars, the vast majority the helium core’s AM is removed during hydrogen shell-burning as the helium core contracts and spins up.”
GWTC-2.1: Deep extended catalog of compact binary coalescences observed by LIGO and Virgo during the first half of the third observing run (2021, unknown): “From a theoretical perspective, BH spin magnitudes are highly uncertain [235,242], with some models [243,244] predicting very low spins ( ∼ 0 .”
The origin of spin in binary black holes (2019, methodology): “From observations of astro-seismology (Fuller et al. 2014; Cantiello et al. 2014), as well as neutron star and white dwarf spins (Heger et al. 2005; Suijs et al. 2008), it is known that this mechanism must be efficient (Spruit 1999, 2002; Fuller et al. 2019).”
Modules for Experiments in Stellar Astrophysics (MESA): Time-dependent Convection, Energy Conservation, Automatic Differentiation, and Infrastructure (2022, methodology): “Currently, mesa-contrib contains routines for the atmospheric T (τ) relations and corresponding MLT parameters implemented by Mosumgaard et al. (2018b) and for angular momentum transport by the enhanced Tayler–Spruit dynamo described by Fuller et al. (2019).”
Evolutionary roads leading to low effective spins, high black hole masses, and O1/O2 rates for LIGO/Virgo binary black holes (2017, methodology): “Super-efficient angular momentum transport is based on the Tayler-Spruit dynamo, which is subsequently modified to include stronger magnetic field generation that allows for more efficient angular momentum transport (Fuller et al. 2019; Ma & Fuller 2019; Fuller & Ma 2019).”